GIS Data Catalog

7.

Aerial Triagulation (AT) of all imagery acquired for 12-inch (1.0ft') pixel resolution orthos using processed Airborn GPS photo centers and new and existing surveyed ground control.

Matching tie points and control were acquired from the 3-inch and 6-inch AT blocks and measured in the 12-inch blocks where appropriate to ensure an accurate match along resolution boundaries.

6.

Rectification and mosaicing of all aerial photos using Inpho OrthoVista software, with the combined input of AT, updated DTM and seamlines.

8.

After initial Quality Assessment (QA) of the tiles by GeoTerra, additional QA was performed by Miller Creek Aerials Mapping (MCA).

This evaluation was both quantitative and qualitative and was performed for a high percentage of tiles in each production zone, usually 50-75%,or greater, of the tiles.

Calls were defined geographically and attributed as to type of issue and signficance.

The RGB tiles were also evaluated by affected participants via a ArcGIS Online data portal maintained by GeoTerra.

Combined calls, those from MCA and from the participants, were assembled.

Review by GeoTerra and MCA, and when needed, by a working group of participants resulted in a final call list of issues that required repair.

Upon completion of all fixes, the tiles went through final approval by GeoTerra and MCA prior to being delivered to King County.

The county then distributed the data to each participant for their defined area of interest.

5.

The most nadir portion of every photo was identified by creating "seamlines" used to stitch the rectified images together.

Seamlines were created using a combination of automatic and manual methods.

Inpho's Ortho Master software was utilized to collect or manually adjust the seamlines polygons.

4.

Update or correction of the existing Digital ElevationModel (DEM) to use for rectifying the images, specifiically for the year 2013-2014 LiDAR data (25% of the 12-inch ortho areas).

All other areas (~75% of the 12-inch orthos) was used as-is, except for minor edits intended to reduce areas of extreme smearing caused by anomlies in the data.

Stereo photography, as a product of the aerial triangulation, was used to update the point data in a 3D stereo environment.

3.

Acquisition of 4-band, 16 bit/band, digital aerial imagery at less than 0.9 ft pixel resolution using multiple Vexcel UltraCam aerial mapping cameras (Hawk, X, Xp and Eagle) during leaf-off and high sun-angle conditions.

Each flight occured with AGPS and IMU.

Enhanced areas of acquisition were acquired at higher image overlap and during a high sun-angle window to minimize buidling lean and shadows in identified dense urban areas.

Post-flight, raw images were processed using propietary UltraMap software into full-histogram (unclipped) images in a final *.TIF format.

2.

Airborne GPS processing.

1.

Flight Planning for 12-inch image acquistion occured in March of 2015 prior to flight.

Multiple aerial flight vendors were subcontracted by GeoTerra to help ensure imagery was captured in a timely manner given seasonal weather and sun angle constraints.

The project was broken into multiple blocks suitable for concurrent and multi-flight acquistion.

All flights were planned and flown to acquire photos with a minimum 60% forward overlap and 30% sidelap.

All 12-inch photos overlapped areas of 3-inch and 6-inch project photography along shared resolution boundaries to ensure proper coverage.