The Lake County GIS Board (Thomas P. Gilles - County Engineer, Edward H. Zupancic - County Auditor and Robert E. Afuldish - County Commissioner) is implementing a Geographic Information System to further improve services to the citizens of Lake County. The County is now ready to convert and integrate various data resources into a fully functional, general-purpose GIS resource. This RFP is being issued in order to secure a professional service contract for the development of digital data including orthophotography, geodetic control; spring 2000 aerial photography, analytical triangulation, Digital Elevation Model creation, compilation of various planimetric features including 2’ contours as well as parcel map conversion.

Upon completion, the digital orthophotos will become available to the public on the Lake County’s Public Access Terminals. Additionally, this data will be made available to other political subdivisions, agencies and the public via an internet/intranet system as well as being published on CD-ROMs.

Section 2 - Background

Lake County is located in northeast Ohio on the shore of Lake Erie about thirty miles east of Cleveland. Its land area is 232 square miles, making it the smallest County in Ohio. Its population of approximately 224,000 is growing due to migration from adjacent Cuyahoga County. In 1997, residential development added an additional $107 million to the real estate tax base; in turn, adding more road mileage to the most recent tally of over 1,300 miles. The City of Painesville is the county seat; there are nine cities, nine villages and five townships. The County provides numerous services including road and building maintenance services, health and community assistance services, law enforcement, human and social services as well as other general and administrative support services. Additionally, Lake County operates a water distribution system, a wastewater collection system, a solid waste disposal system and a solid waste-recycling program. See Appendix A: Lake County Profile (including county map).

The Lake County auditor maintains a database for approximately 103,500 parcels.

The Auditor’s Office has a staff of 34 who handled 5,425 transfers in 1998 (4,433 exempt). Approximately 300 sublots are recorded per year.

The auditor’s data processing environment is dominated by two systems. The Real Estate and Land Management (REALM) system from Manitron/Sabre Systems, Inc. provides for the real property transfer functions of the Auditor’s Office. The Integrated Assessment System (IAS) from Cole, Layer, Trumble Co. provides for the property appraisal functions of the auditor.

Lake County will be implementing the GIS using the suite of products from Environmental Systems Research Institute (ESRI) and other related software programs.

Lake County has invested considerable time planning for the implementation of GIS. For your information:

· An extensive pilot project has been completed for the area of Fairport Village. See the GIS and Ortho folders in the enclosed CD-ROM entitled “Supplemental” in Appendix B - Fairport Harbor Village pilot project. These contain ArcView shapefiles and digital orthophotos from the pilot project.

· A 1990 GIS Implementation Plan has been updated. See the Approach folder in the enclosed CD-ROM entitled “Supplemental” for the Word ’97 file named “report”: Lake County GIS – A Recommended Approach.

· A Functional Requirements and Detailed Database Design Report is currently being developed. Through staff interviews and analysis of existing geo-related data, this report will detail and provide recommendations regarding:

· GIS application priorities

· GIS Requirements Definition Workpaper

· existing digital data resources and potential issues of integration into the GIS

· existing analog geo-related data, suitability and potential conversion issues

· logical database design including an entity relationship diagram

· physical data model

· GIS Design Report

Given that this report was not complete in time for the release of this RFP, detailed specifications from this Report will be provided to the successful Bidder. This will include definitions for the compilation of planimetric and cadastral features, ArcInfo graphic representation requirements, data source analysis’, data structuring, e.g. parcel tiling, geodatabase considerations, data storage/library structure, as well as annotation and attribute requirements.

Scope of Services

Overview

The following is an overview of the services included in this procurement:

· Conducting control survey, pre-flight control targeting

· Conducting aerial photography of the county producing diapositives and aerial triangulation information

· Compiling a Digital Elevation Model (DEM) suitable for the generation of contours at 2' intervals for the entire project area compiled in accordance with ASPRS standards for Class 1 Large-scale Maps.

· Preparing black & white digital orthophotography at 1”=100’ scale with 0.5 foot pixel resolution (plus color orthophotography at 1.0 foot pixel – County option)

· Planimetric features including road pavement edges, bridges, railroads, major structures, topography (2’ contours), street centerlines and hydrography.

· Developing digital cadastral features (County option)

Pilot Project

A pilot project will be undertaken by the Bidder, coverage to be mutually agreed upon (approximately 3 square miles). Pilot deliveries will include digital orthophotos, planimetric mapping, and DEM, plus one set of check plots and confirmation plots, as necessary. The objective of the pilot shall be to:

· Execute and validate all procedures

· Produce a model database covering the pilot area

· Finalize quality control procedures

· Finalize database designs

· Evaluate and approve all specified products

Section 3 - Aerial Photography Requirements

3.01 Film

Aerial film shall have a fine grain, unexpired panchromatic emulsion on a dimensionally stable and clear polyester base. Only one type of film shall be utilized throughout the entire project and must meet or exceed ASPRS standards for film condition, storage and handling, exposure, processing and drying. Exposures acquired during any reflights shall be subject to these same standards and the Bidder shall make every effort to acquire these exposures so that conditions during reflight are as close as possible to conditions which existed during the original photography.

Extreme care shall be exercised to insure proper exposure to minimize vignetting due to differential exposure. This differential shall not exceed that which would result from a basic 1/3 stop difference in exposure. All film shall be exposed using the fastest shutter speed possible when the aperture is set at its optimum value in consideration of the optical resolution and image motion.

The conditions of the film stock to be used shall be such that when the unexposed film is processed:

It shall be free of stains, discoloration, or brittleness that can be attributed to aging or improper storage; and

The base-plus-fog density for all negative films shall conform to the manufacturer’s predicted density levels.

Exposure of the film shall be in accordance with the manufacturer’s recommendations and with a goal toward achieving density requirements. The negatives shall be clear and sharp in detail, free from light streaks and static marks, and of uniform tone and degree of contrast to permit ground details to show clearly in all scene reflectance, with particular emphasis on pattern recognition in the shadow areas.

In accordance with ASPRS standards, Bidder will provide a log of the static and variable flight line data for each roll of exposed aerial film:

Static Data

§ Last names of crew members

§ Camera type and serial number

§ Lens type, serial number, and calibrated focal length

§ Magazine number

§ Film type, emulsion batch, roll, cut, and slit numbers and expiration date as shown on the manufacturer's packaging

§ Filter type and number

Variable Flight Line Data

§ Altitude correction data (required each time the aircraft ascends or changes altitude)

§ Brief description of atmospheric conditions

§ Aperture setting

§ Shutter speed

§ Nominal photo scale

§ Area covered

§ Date of exposure

§ Direction of flight

§ % of forward overlap

§ Beginning and ending exposure numbers (referenced to the camera counter)

§ Start and stop times (local standard time)

Remarks including:

§ Complete or incomplete flight line, blanks frames, run-off, rejections, and reasons for rejections

§ Any unusual situation that occurs during the flightline

The exposed aerial film is the property of the Lake County Engineer’s Office and shall be stored free by the Bidder until such time as needed. All aerial film will be stored and properly safeguarded according to proper archival procedures for the storage of photographic material. These procedures shall be agreed to by the Lake County Engineer’s Office.

Each processed roll or partial roll of aerial film shall be kept in roll form, on the spool, and in the plastic container supplied by the film manufacturer. Rejected exposures shall not be removed from any roll.

3.02 Storage and Handling

Storage and handling of all photographic film shall be in accordance with the manufacturer's recommendation. All aerial film shall be stored in the original containers to prevent any exchange of moisture between the rolls and their surroundings up to the time they are exposed. The film shall not be rolled tightly on spools or in any way stretched, buckled, distorted, or exposed to direct sunlight or other sources of heat.

The container for each roll of aerial film shall be made of plastic, shall not exceed 10” in diameter, shall contain no more than 500’ of film, and shall be the property of the Lake County Engineer’s Office. It shall be clearly labeled with the name of the County; name of the Bidder; date of the photography; flight and exposure numbers (sequential number of the first and last exposures); type and serial number of the camera; the type, serial number and calibrated focal length in millimeters of the camera lens; film roll number and the approximate scale of the photographic negatives.

Adverse storage conditions can affect the emulsion layers, as well as overall sensitivity. Unexposed color films that are to be stored for several months shall be stored at 0 to –10 degrees Fahrenheit (-18 to –23 degrees Celsius).

3.03 Processing and Drying

All black and white aerial film shall be processed in a sensitometrically controlled process using the manufacturer’s recommended process-monitoring system. Each roll of aerial film shall have an unexposed leader at least ten frames in length. This unexposed leader will be used to expose a calibrated 21-step sensitometric wedge (in .15 nominal density increments) before processing. Whenever a roll of aerial film is used in a discontinuous fashion such as from one day to the next or from a morning flight to an afternoon flight, a spacer at least four frames in length shall be rolled forward just prior to the commencement of taking new photographs.

The film shall be thoroughly fixed and washed to ensure archival quality. The residual thio-sulfate content of the processed black and white film should not exceed 0.04 milligrams per square inch as measured using a Kodak Hypo Estimator and Hypo Test Solution HT-2 or other approved method.

Processing and drying of film shall be carried out without affecting the metric quality. At no time shall the film be subjected to extreme temperature and humidity changes.

The processed film shall be free from chemicals, stains, tears, scratches, abrasions, watermarks, finger marks, lint, dirt, light streaks, static marks, and any other physical defects that would interfere with the intended purpose of the photography.

3.04 Metric Quality of Processed Film

The original processed film or contact diapositives produced from them shall not contain residual Y-parallaxes after relative orientation in excess of 20 µm anywhere in the model. The dimensional change in any direction across a 9" distance shall not exceed 127µm.

3.05 Image Quality of Processed Film

The imagery on the aerial film shall be clear and sharp and evenly exposed across the format. The film shall be free from clouds, cloud shadows, smoke, haze, snow, shadows, crimps, scratches, and any other blemishes which interfere with the intended purpose of photography. Allowances will be made for unavoidable shadows or reflectance from water bodies.

3.06 Processing

All negatives, diapositives, prints, etc. shall be processed under "clean darkroom" conditions. They shall have fine grain quality, normal density and such tone and degree of contrast that photographic details show clearly in both the dark-toned and highlighted areas. They shall be free from clouds, cloud shadows, smoke, haze, snow, shadows, crimps, spots, scratches, chemical stains and any other blemishes which might detract from their intended usefulness.

3.07 Color Orthophoto option

Lake County requires black and white photography; however, the County is potentially interested in color photography. The cost for the color digital orthophotography should be included on the Itemized Cost Form, not as an alternative bid.

3.08 Camera

The aerial camera shall be a precision vertical format aerial mapping camera featuring differential exposure control and forward motion compensating device, and shall be equipped with a low distortion, high resolution lens. The camera shall be mounted in the aircraft in such a manner that the film advances parallel with the line of flight allowing uncut film negatives to be viewed stereoscopically.

The lens must have a maximum aperture of f/4 or f4.5, and must also meet the requirements outlined below, based upon a U.S. Geological Survey Report of Calibration not more than three years old.

The calibrated focal length of the lens shall be 153 millimeters plus, or minus 3 millimeters (6” focal length). The usable angular field must be at least 90°. A glass filter with a metallic antivignetting coating shall be used. The filter shall have surfaces parallel within 10 seconds of arc, and its optical quality shall be such that its use shall not cause an undesirable reduction in image definition. The camera shall expose a 9”x 9” size negative and produce a minimum of eight fiducial marks in each negative.

The camera shall produce eight fiducial marks, located in each corner and at the center of each side, which are clear and well defined on each negative. Corner fiducial marks shall form a quadrilateral whose sides are equal within 0.050 mm. Mid-side fiducial marks shall be equidistant within 0.050 mm from adjacent corner fiducial marks. Lines joining opposite pairs of fiducial marks shall intersect at an angle of 90 degrees + 30 seconds and indicate the true position of the principal point of autocollimation within 0.030 mm. The fiducial centers and the point of symmetry shall fall within a 0.030-mm radius circle around the principal point of autocollimation. No glass shall be permitted between the lens and the film. Maximum shutter speed and aperture setting will be used to minimize image motion.

The lens should have an area weighted average resolution (AWAR) of at least 85.0 line pairs per millimeter, as determined by the U.S. Geological Survey Report of Calibration.

The film shall be held in the intended image plane during exposure to maintain sharp focus and hold image distortion to less than that which will produce 20 microns of y-parallax after relative orientation anywhere in the model. The lens shall be corrected for the spectral range of the film used.

3.09 Stereomodel flatness

The average departure from flatness (a negative scale) to computer-simulated stereomodels may not exceed 13 µm for any symmetrical point tested by USGS. The difference between the highest and lowest value shall not exceed 25 µm. The average of values given for points tested by USGS (which are averages themselves) shall not exceed 6 µm

3.10 Flight Data

The following data is to appear on the inter-frame margin of each negative as clear, uniformly illuminated images of the actual display instruments.

1. Time of day clock, set in either standard or daylight savings time, as appropriate.

2. Altimeter reading and feet or meters above mean sea level.

3. Exposure counter, which shall also display the camera identification number and the lens focal length in inches or millimeters.

The Platen ID # should be exposed on each negative, or at the beginning and end of each role of film used.

3.11 Calibration

Each camera lens unit shall have been calibrated, tested, and certified by the camera manufacturer or by a calibration center, recognized internationally or approved by the camera manufacturer. However, when there is any reason to believe the dimensional relationship of the lens, fiducial marks, and film plane have been disturbed by partial disassembly or unusual mechanical shock, the camera must be submitted for recalibration at the Bidder’s expense.

A U.S.G.S. camera calibration report, no more than three years old, shall be submitted with the response to these technical specifications for each aerial camera to be used to assure that the camera lens, focal length, light filter, shutter, image format, and its platen are all photogrammetrically adequate and within acceptable limits. The absence of a calibration report verifying that the camera meets the specified requirements may be cause for disqualification of the Bidder. The Bidder will be ultimately responsible for errors caused as a result of incorrect calibration of the camera.

The organization conducting the photo mission shall hold a valid calibration certificate and shall supply a copy to the client or the user on request. The calibration certificate shall contain the following information:

§ name and address of calibration facility

§ date of calibration

§ serial number of lens unit

§ calibrated focal length (principal distance)

§ radial distortion in micrometers at intervals not exceeding 10 mm along each of the four semi-diagonals referred to the axis of best symmetry

§ distances between fiducial marks sides and diagonals or their rectangular coordinates

§ position of the principal point of autocollimation or of best symmetry with respect to the fiducial center

§ radial and tangential resolution for the lens, issued by the manufacturer or after optical readjustment of the lens unit

The measured distortion shall fall within the limit defined by the manufacturer for the lens type.

3.12 Camera Mount

The camera shall be installed in mounts that attenuate the effects of aircraft vibration. The mounts should be regularly serviced and maintained.

3.13 Filters

Only optical filters provided by the lens manufacturer meeting the same optical specifications shall be used.

The light fall-off in cameras having an angle of view larger than 60 degrees shall be compensated by a graded (anti-vignetting) filter.

3.14 Time of Photography

Photography is to be performed in late winter/early spring of 2000 prior to onset of spring vegetation. Photography shall not be secured when the ground is obscured by haze, snow, smoke, dust, flood waters, or environmental factors that may obscure ground detail. Clouds and/or shadows of clouds shall not appear in the photograph. The solar altitude shall be defined by the application but in general it should not be less than 30 degrees when aerial negatives are exposed. It should be, therefore, flown generally between the hours of 10AM and 2PM Eastern Standard Time.

3.15 Aircraft and Crews

The following ASPRS standards pertaining to the photographic mission shall be met or exceeded:

· Physical checking, inspection, and settings of cameras, lenses, filters, ports, magazines, transports, drive mechanisms, and shutters to ensure that all components are free of defects, foreign particles, and condensation

· Forward overlap and side overlap requirements

· Departures from required flight heights and changes in aircraft course documented

· Compensation for aircraft crab and tilt.

All aircraft shall be maintained and operated in accordance with regulations of the Federal Aviation Administration and the Civil Aeronautics Board. The recommended FAA preflight inspection of the aircraft and instruments must be performed prior to each photographic mission. Aircraft shall have a service ceiling (with operating load of crew, camera, film, oxygen and other required equipment) not less than 5% above the highest altitude necessary to achieve the smallest photographic scale required. If the project is in controlled air space, the appropriate Air Traffic Control Center (ARTCC) must be contacted. The Willoughby Lost Nation Airport and Casement Airport in Painesville are located in the County to serve private aircraft. The Cuyahoga County Airport, which also serves private aircraft, is located along the western boundary of Lake County.

Individual crewmembers shall have two years or more apprenticeship in flying photographic missions for aerial surveys. In addition, it is desirable crewmembers have had meaningful prior experience with the same type camera and aircraft to which they are assigned.

3.16 Photographic Mission

The camera magazine must be clean and firmly seated on the camera. The transport system must be operating properly and the correct information entered into the data block recording devices. The exposure, frame counter number, and fiducial lights must be set for the sensitivity of the film type being used in the camera. Cycle the camera to assure the drive mechanism and shutter are operating smoothly and complete the basic data sections of the photographic flight report.

Black and white aerial photography at a negative scale of 1" = 600' shall be obtained. Bidders may suggest alternative aerial photographic scales to be used for this project in their response and shall include the reasoning for suggesting an alternative scale, e.g. cost decrease, less distortion, etc.

Forward overlap in the line of flight shall average not less than 57% or more than 62% at the mean elevation of the terrain, unless otherwise specified. Individual forward overlaps shall not be less than 55% or more than 68%, excepting the situation where in a forward overlap in areas of low elevation must exceed 68% to attain the minimum 55% forward overlap in adjacent areas of higher elevation. Wherever there is a change in direction between two flight lines (other than between adjacent parallel flight lines) junction areas between the adjoining flight lines shall be covered stereoscopically by both lines.

Side Overlap between adjacent parallel flight lines shall be 30% +/- 5% at the mean elevation of the terrain. In addition, any point on the flight line as flown shall not deviate from the flight plan location by a distance greater than 10% of the width of coverage of the photograph.

Departures from flight heights required to produce the desired photo scale shall not exceed -2% or +5% unless changed by Air Route Traffic Control Centers.

Changes in the course of the aircraft between successive overlapping photographs within a flight line shall not exceed 3 degrees.

While exposing aerial photography, the camera shall be compensated for crab of the aircraft, with a resultant error not exceeding 3 degrees.

The tilt within a single frame shall not exceed 3 degrees nor shall the difference in tilt between two consecutive overlapping frames within a flight line exceed 4 degrees. The average tilt for all negatives of the same nominal scale shall not exceed 1 degree.

The combined effect of aircraft course corrections, crab and tilt shall result in an apparent crab not greater than 5 degrees on successive photographs. Apparent crab is defined as the angle between a line joining fiducial marks in the direction of flight and the line between the indicated principal point and the conjugate image of the of the indicated principal point of the adjacent photograph within the same line of flight.

Every effort shall be made to avoid breaks within individual flight lines. Where breaks within a flight line are necessary, the entire flight line composed of the resulting segments shall meet all of the requirements set forth in these Specifications. Where breaks occur, these shall have an overlap of at least four frames to ensure a stereo model of overlap or tie. All photos within a single flight line shall be acquired with the same aerial camera and with the camera oriented in the same direction.

Exposures acquired to replace rejected, damaged, lost or otherwise destroyed exposures shall fully conform to these Specifications. Replacement exposures shall be acquired with the same aerial camera(s) used to acquire the original exposures and shall be exposed as nearly as possible to the same day and lighting conditions as the original exposures.

The final 10 frames (or more) on each roll shall be reserved for test processing purposes. These test frames shall be representative of the terrain covered on the exposed roll. The test frames should be exposed at the same altitude; relative aperture and shutter speed as used for majority of the roll. When possible, the process should be adjusted for improper exposure.

3.17 Preliminary Checks

Each roll of aerial film shall be processed within one week after it is exposed. Navigation of the flight lines and image quality shall be quick-checked for compliance with these specifications. An image quality report shall be forwarded within one week of the flights. Vendor shall specify in the proposal the contents of the image quality report.

As soon as possible after processing each roll of aerial film, diapositives shall be prepared for two consecutive stereo models. The models shall be selected at a random location within each roll of film. Each model pair shall be checked in a stereo-plotter for the ability to clear parallax and to transfer scale between models. Results of these tests shall be documented to identify model numbers tested, dates of tests, Z instrument readings for points read in the triple lap area. The purpose of the test is to determine if the camera functioned properly during the mission and the film was in good contact with camera platen at the time of exposure. If the test indicates a malfunction, the photography must be reflown at no additional cost to the County.

Reflights shall be immediately (within one week) ordered for the purpose of securing replacement exposures for all frames which fail to meet minimum standards set forth in these specifications, provided ground conditions have not yet terminated the photographic "season." Unacceptable aerial photography shall be reflown by the Bidder at no additional cost to Lake County, with the reflight coverage overlapping the acceptable photography by at least two stereomodels.

3.18 Film titling

All lettering shall be positioned as closely as possible to the inside leading edge of the format of the exposure. The characters used for making the exposures shall be 3/16 inch, stamped with opaque ink to avoid deformation of the film as what is manifested with heat embossed titlers. The lettering shall clearly show on all copies of the photographs and in the positions specified by the requester.

3.19 Documentation

Each exposure shall be marked beginning in the left-forward corner of the format with the numerical abbreviation of the date in the American usage.

Each exposure shall be clearly labeled by mechanical means at the north edge of the negative just outside of the image area without obscuring the fiducial marks. The labeling shall include the following information at a minimum: numerical abbreviation of the month, day and year; the number of the flight line; the sequential number of the exposure on the flight line; the scale of the photography using a relational fraction; and the project designation of Lake2000

The time of day in hours and minutes shall be shown on the first and last exposures of each flight line midway between the date and the middle forward fiducial. The roll-strip-exposure number shall be marked at the right-forward corner of the format. All film on a single spool shall bear the same unique roll number. The photographic strips shall be flown and numbered as specified in the Detail Sheet in an unbroken series. The nadir of each exposure shall be entered into a database.

Bidder shall produce Federal Geographic Data Committee (FGDC) compliant metadata for the aerial photography/flight.

3.20 Spot Photos

Aerial photos will be taken directly overhead to integrate into the digital ortho image for all structures over 10 stories in height, highway overpasses, and other bridges. If the Bidder has an alternative methodology, include it as an alternative. An alternative can include increased forward and side overlay (i.e. 80% forward lap and 45-55% side lap).

The scale of the imagery rounded to the nearest whole thousand (e.g. 1:31680 will be 32000) shall be positioned immediately to the right of the middle forward fiducial.

Aerial Photography Product Specifications

3.21 Photo indexes

The Bidder shall prepare a black and white photo index by joining together the contact prints (or a set of reduced size prints), trimmed to the image area. The prints shall be carefully matched so that the corresponding images overlap and all photo numbers are visible. This original composite of contact prints shall be photocopied, reduced in scale, and reproduced on uniform size sheets.

Maximum sheet size will be 30" x 40". The index shall contain the names of cities, towns, major roads, and other prominent geographic features for orientation purposes. The index shall also include title information identifying the County, name of the Bidder, date and scale of aerial photography, type of camera and focal length of its lens, the scale of the photo index, and north arrow.

Match lines are required for all flight line divisions, whether on single or multiple index sheets. Photo indexes shall be oriented to the north and the title information should appear in the south or east margin of each index. Deliverable products required include the photo index negative; one (l) mylar-based, screened positive; and one (1) photographic positive on medium-weight, semi-matte paper.

In addition, ARC/INFO coverages shall be created and delivered:

· Line coverage depicting the flight. Attributes attached to each arc will include altitude, direction, pilot name and date of flight.

· Point coverage with the x , y coordinate of each photo center point (nadir). Attributes attached to each point will include correlated diapositive and contact print number, film roll number, flight line, and frame number.

3.22 Contact prints

One set of original aerial contact prints shall be made on an automatic dodging printer on medium weight resin-coated paper on which ink and pencil can be used on both sides. All prints shall be clear and free from chemicals, stains, blemishes, fog, streaks, scratches or any defects that would render them unusable. One set of unmarked contact prints prepared from the original aerial photographic negatives will be delivered to the County two weeks after the flight. The County will review the contact prints to determine adherence to the contract specifications. The aerial triangulation process will begin after the County has accepted the aerial photography.

The photographic emulsion shall be of fine grain and have a suitable light sensitivity range and contrast for the making of prints from the aerial film exposed under the contract. Outdated materials shall not be used.

Processing, including exposure, development, fixation, washing, and drying of all photographic materials, shall result in finished photographic prints having a fine grain quality, a normal, uniform density, and such tone and contrast that all photographic details shall show clearly within the dark and light tone areas as well as in areas with intermediate tones. Adequate grades of contact paper and proper laboratory procedures shall be used to achieve the best prints possible. Excessive variance in tone or contrast between adjoining prints, as determined by Lake County, shall be cause for rejection.

Photographic prints shall be trimmed as specified by the user. When trimmed always leave the camera fiducial marks and other information recorded in the border of each image. Prints showing fiducial marks of inadequate clarity and definition, or prints omitting fiducial marks, shall be rejected.

All prints shall be clear and free from chemical stains, blemishes, uneven spots, air bells, light streaks or fog, and other defects that would, in the opinion of Lake County, interfere with their intended purpose. Prints shall be delivered to the owner in a smooth, flat, and usable condition.

NOTE: The material for Aerial Photography Section has been adapted from draft specifications published by the American Society for Photogrammetry and Remote Sensing, ASPRS Professional Practice Division, Specifications and Standards Committee internet web page. (http://www.asprs.org/asprs). The material for Camera and Associated Equipment has been adapted from "Specifications for Vertical Aerial Photography, 2nd Edition," The British Air Survey Association and the Land Surveyors Division of the Royal Institution of Chartered Surveyors, July 1984. Additional reference included the Ohio Department of Aerial Engineering – Minimum Specifications for Aerial Photography and Mapping, November 1996.

Section 4 - Analytical Triangulation and Digital Orthophotography Requirements

General

Sufficient horizontal and vertical control surveys shall be established by the Bidder to support the subsequent production of digital orthophotography and photogrammetric mapping. The Bidder shall recover any existing control, establish new control, if necessary, and position targets prior to the aerial photography. The Bidder shall indicate in their response to these specifications the estimated total number of horizontal and vertical control points that shall be required to satisfy the project requirements.

Bidder shall also provide a detailed description of the equipment and methods to be used to complete the horizontal and vertical control survey work in their Technical Plan of Operations. At the County’s option, horizontal and vertical control points may be monumented by the Bidder in the field with permanent monuments.

The Bidder may propose to utilize all or any portion of the control information from the 1993 GPS control survey. Any additional monumentation that is suggested shall be indicated as such and included in this proposal as an alternative option.

Creation of the digital orthophoto shall utilize several types of inputs. These inputs shall include:

1) The unrectified raster image file acquired from the scanning of the aerial photography

2) A digital elevation model

3) The photo-identifiable image and ground coordinates of ground control positions (a minimum of four) acquired from aerotriangulation

4) Camera calibration information.

These four input sources shall be used to register the raw image file mathematically to the data to determine the location of the pixels with respect to the ground and to remove relief displacement from the image file.

With the proposal, Bidder shall provide sample, tiled (preferably TIFF format) black & white digital orthophotos from previous clients (if available) with the following characteristics:

· 1”=100’ scale, 0.5 foot pixel resolution, negative scale of 600’.

· 1”=100’ scale, 0.5 foot pixel resolution, negative scale of 800’.

Project Area

The project area encompasses Lake County and a 100’ buffer beyond the county boundary except along the shoreline of Lake Erie where the orthophotos shall be clipped 200’ from the shoreline as depicted in the aerial photography.

General Guarantee

All Bidders shall indicate that, if awarded the contract, they would be willing to guarantee that their survey work meets the specifications for the project. The written guarantee would insure that if errors or omissions were found later, the Bidder would resolve them in a timely manner. The guarantee shall specify that the County shall guarantee the services provided by the Bidder against errors for 10 years from the date of final acceptance.

Survey Control Specifications

4.01 Existing Control

As a part of the development of the countywide GIS system, the Lake County Engineer’s Office contracted for the development of a Global Positioning System (GPS) control survey for a county-wide network densification. Work included positioning and “Bluebooking” 5 existing benchmarks throughout the county to National Geodetic Survey (NGS) first order standards. There were 121 total new GPS stations established which were tied to 10 existing horizontal stations and 10 existing vertical stations. These control points shall be utilized to develop a Digital Elevation Model (DEM) used to rectify the digital aerial photos. All horizontal control surveys were based on the Ohio State Plane Coordinate System, North Zone 4301, NAD 1983 and NAVD 1988. The intended relative positional accuracy of first order (1:100,000, 10ppm) was met for all stations, based upon relative station precisions (over-constrained) loop closures and repeat baseline analysis. See Appendix C – Control Survey Information.

The Bidder shall also make maximum use of other horizontal and vertical control established by Lake County. Information on the location of other existing control should be obtained by contacting NGS or other agencies as appropriate.

4.02 Horizontal Control Surveys

At a minimum, all new horizontal control that is placed for this project, if more is required, should be to an accuracy level of NGS First Order. All horizontal control shall be established by appropriate GPS technology, or by traverse, as necessary. Federal Geodetic Control Subcommittee standards for instrumentation, field observations, and data reduction shall be followed as applicable to First Order survey.

4.03 Ground Coordinate Systems

All horizontal ground control shall be determined in the Ohio State Plane Coordinate System (North Zone), using the North American Datum (NAD) 1983. All final control shall be identified in geodetic coordinates (NAD 83) of latitude and longitude and in feet. The U.S. survey foot shall be used for all meter to feet conversions.

4.04 Control

The 9”x9” contact prints of the photography must be used for selecting points and locating paneled control. All photo-identifiable control points for analytic triangulation must be located and symbolized on the image side of the photographs and labeled with coordinate values on the reverse side.