Aerial Mapping Projects

ALS, Inc. began the multi-year aerial mapping project with a client in 1999 to provide orthometeric images of Harris, Montgomery, Fort Bend and Brazoria Counties. In 2001, the project was extended to provide updated imagery. The coverage area exceeded 5,000 square miles. The final deliverables were digital files (MrSID format with ½ meter and 1 foot color pixels).

A diapositive of the color photography was created and scanned using a Z/I PhotoScan PS-1. In later phases the film was scanned using our new PS-2 role feed scanner. The resulting digital image was bridged, rectified, dodged, and mosaiced in a Z/I Image Station. The final product was reviewed during each process to ensure quality and completeness. The deliverable files were then delivered by Snap Server to H-GAC. ALS, Inc. extended a mapping sheet facet pattern which has become the accepted standard for wide area mapping in Harris and surrounding counties.

Today, ALS, Inc.’s images from this project have been widely used for planning and as background for engineering drawings. A collateral product made available to the community by ALS, Inc. is MrSID mosaic files created from the original files. These files have been used by cities, economic development corporations, engineers, surveyors and GIS specialists.


mappingALS, Inc. was contracted by Texas Department of Transportation to perform complete aerial mapping on the Hardy Toll Road from Greens Road to Gulfbank Road. ALS, Inc. was sub-contracted to provide services on the continuation of the project from Gulfbank Road to IH 610.

The project included establishing the horizontal and vertical controls to support aerial photogrammetry. ALS, Inc. generated Digital Terrain Models (DTMs) to develop the surface. Digital design files of the DTM and planemetric detail were also produced. ALS, Inc. staff used CAD software to create the final DTM and planemetric detail. MicroStation V8 and Leica GPS reduction software were used to determine coordinates. Intergraph’s suite of photogrammetry products were used to collect aerial photography and MicroStation V8 was used to edit the final drawings. Bently’s Geomedia was used to collect the orthoimages.