Building polygons were updated from the existing City GIS mapping data.

May 2015 stereo photography was used to photogrammetrically evaluate the existing building polygon coverages compared to current conditions. Data was modified to reflect any change (addition or removal) greater than 100 square feet. Porch awnings, deck awnings and similar covers not permanently integrated with the main structure were not included. Planimetric mapping was compiled to industrry standards using established methodologies, flight altitudes, control and processes to meet or exceed ASPRS Class 1 accuracies for 1"=100' mapping, consistent with existing data sets and past mapping projects. Field checks were not performed.

In general, buildings and structures less than 100 square feet were not included.

ATTRIBUTE DESCRIPTION

BUILDING (most buildings, including commercial, residential, sheds, garages and other buildings generally larger than 100 square feet)

MOBILEHOME (manufactured and mobile homes in obvious mobile home parks)

GREENHOUSE (transparent building)

TANK (large, permanent tanks)

STRUCTURE (miscellaneous large permanent structures)

GENERAL PROCESS

Prepared by

DAVID C. SMITH & ASSOCIATES, INC.1734 SE Tacoma Street, Portland, Oregon, 97202

http://www.davidsmithmapping.com

info@davidsmithmapping.com

Job #: 2334

Supervising Professionals: Scott Smith, Certified Photogrammetrist, Oregon Professional Photogrammetrist # 38670 RPP Doug Smith, Certified Photogrammetrist, Oregon Professional Engineer # 16707

Source photography

Camera: UltraCam XP, S/N UC-SXp-CI-10411033 (Bergman Photographic Services, Inc.)

Calibration Date: 12/11/2012 (Factory Calibration)

NOTE: Standard USGS calibration does not apply to digital cameras. USGS certifies the camera manufacture and factory calibration process but does not calibrate individual cameras.

Calibrated Focal Length: 100.5 mm

Date of Photography: 5/29/2015 Approx. Time of Flight: 11:00 a.m. to 1:00 p.m., Pacific Daylight Time

Flight specifications

0.3' pixel Ground Sample Distance(maximium)

Nominal Flight Altitude: 4,600' Above Ground Level

Nominal Photo Scale: 1058 ft/inch (1:12700)

Control

Datum: NAD '83/'2011, U.S. Survey Feet

Projection: LAMBERT CONICAL, Washington, SOUTH ZONE

Ground Control: Air-borne GPS control was acquired and tied to new City of Olympia control. Existing City ground control was also used to provide datum consistency. New premarks and survey points were established.

Aerotriangualtion Solution: Aerotriangulation was performed to industry standards as supported by photo scale and available existing City control. Aerotriangulation solution was designed to support 1"=50' scale, 2' contour mapping within the UGB extents of existing control and 1"=50' scale, Accuracies for discrete aerotriangulation points and supported stereomodel measurements are: +/- 0.5' horizontal and vertical.

Data set Accuracy

HORIZONATAL ACCURACY: Compiled to meet ASPRS Class 1 accuracies for 1"=100' scale mapping, consistent with existing data sets from past mapping work. This is equal to an ASPRS 2014 30 cm RMSE horizontal accuracy class equating to a circular horizontal accuracy of +/- 2.4' at a 95% confidence level.

VERTICAL ACCURACY: NOT APPLICABLE

Data Collection and Update Process

Softcopy photogrammetric workstations were used to view and evaluate existing City GIS impervious surface data against current (2015) stereo imagery using 3D softcopy photogrammetry methods for planimetric data updates. Photogrammetric vector linework was collected and coded by feature type. Impervious area polygons were built using polygon ID points to identify selected impervious surface polygons. Final polygon builds were generated using automated methods and manually reviewed for consistency and completeness.