Orthophotography FAQ

What is the graphic format of the aerial photography? 

TIFF (Tagged Image File Format)
MrSID (Multiresolution Seamless Image Database)
ECW (Enhanced Compression Wavelet) - only at the participants request

What is a .tiff?

A .tiff is a graphic image, much like a .bmp or .jpeg which includes assigned geographic coordinates either embedded or in a separate world file (.tfw).   Rather than lay on top of one another, the positional information in the TIFF allows them to lay side by side.

What is resolution?

Resolution is the size of each pixel in the graphic file. Much like a television screen, aerial photography is a collection of small boxes, or pixels, each having an assigned color. Together the pixels make up an aerial photo. The smaller the pixel the more precise (clear) the orthophoto, however the file size and cost increase with the resolution.

What resolutions are available and how much do they cost? 

Aerial photography costs are based on the year flown and the resolution. The following chart summarizes the cost per tile for the years and resolutions available.

What is the file size for a tile? 

3 inch = 280 MB 
6 inch = 71.5 MB 
1 foot = 17.9 MB 
2 foot = 4.5 MB 
4 foot = 1.1 MB 
8 foot = 280 KB

How can I view specifications and/or download samples? 
Specifications and sample images can be found on each ortho project page.


Can aerial photography be certified for legal purposes?

An aerial image can be certified as a NCTCOG product only. Certification costs $50 per item and must be done in person at NCTCOG by a notary public. Contact Shelley Broyles at 817-695-9156 for more information.  To certify the accuracy of the aerial image, contact the company which flew the aerials (see below).

Can TIFF files be used in AutoCAD or Microstation?

Yes, if the software version can read a TIFF file with an associated world (.tfw) file.

Who flew the aerial photography? 

2001 - Vargis, LLC
2003 - Pixxures Inc. and Dallas Aerials Surveys Inc. 
2005 - Bohannan Huston
2007 - Bohannan Huston 
2009 - Bohannan Huston 
2011 - Sanborn
2013 - Woolpert
2015 - Woolpert
2017 - Woolpert

What time of year is the aerial photography taken? 

Aerial photography is flown in January through March (leaf-off) when the visibility of ground features is best.

Are the street names that appear on DFWmaps.com on the aerial photography? 

No, street names are not included on NCTCOG aerial photography.  To view the streets you can download streets and other basemap layers from our Open Data site and overlay them on the orthophotography.