HJW GeoSpatial, Inc.- Services- Orthophoto Production

HJW GeoSpatial Services

Orthophoto Production
Orthophotos are photographic images that have been corrected to remove displacements caused by camera tilt and terrain relief. They can be seamlessly mosaicked into a tiled dataset for use with any GIS or vector overlay.

HJW’s orthophoto production software, OrthoView, was developed in-house by our staff, and is specially tailored to our workflow. Our intimate knowledge of the software ensures that orthophotos meet our stringent quality requirements. It is optimized for processing efficiency, which translates to quick turnaround time. Our aircraft is equipped with an airborne GPS/IMU system which aids in the orientation of the photography. We are one of the few companies that have the IMU component, which gives us higher accuracy capabilities for orthophotos and mapping over rough terrain and water. After osrthophotos are produced, they are mosaicked, radiometrically balanced, and cut into tiles customized for the project.

Orthophotos produced by HJW exceed industry standards in the following ways:

1. DTM corrections are made to accommodate man-made terrain. Since DTMs represent the terrain and not man-made structures, bridges and other transportation features may not be properly represented, causing warping in the orthophoto. HJW corrects this problem by manually collecting DTM data for these features and producing more representative orthophotos.

2. Seam mosaicking is done manually by a technician who ensures that adjacent orthophoto boundaries do not interfere with buildings or other man-made structures above the ground.

more about orthophotos

In the figure, the left images show areas where automatic seam lines interfere with buildings, causing a shifting effect in the mosaic. The images on the right represent the same areas, but with seam lines manually diverted around the building.