Q. How do I find out if you have aerial photo coverage of my site?

A. Visit our library coverage list for your state and transmit an outline of your site on a USGS, Tax map, road map, or other. (See sample request outline)

Q. What is the date and scale of library coverage?

A. This information varies and is available on a tabulated list by town name. To find out more visit our library coverage lists. (Find your state and then town)

Q. Does the company own its own aircraft and cartographic aerial camera?

A. Yes, Aerial photography is captured with our company owned Cessna 206 turbo aircrafts, which is configured specifically for aerial mapping.

Q. How do I have a custom flight set up to cover my site?

A. Transmit to us an outline of your site on a USGS, Tax map, road map, or other. (See sample request outline)

Q. How soon can a photo mission be flown?

A. Normally within 10 days, depending on weather conditions and site suitability.

Q. How soon after the flight can I expect to receive photos with ground control selected and identified?

A. Normally within 3-5 days for black and white imagery.

Q. What mapping scale and contour interval is possible from existing library?

A. All imagery in our library is suitable for mapping 2' contours. Scale will vary with altitude of photography from a range of 1"=40' to 1"=100' or greater.

Q. What is the turn-around time to deliver completed mapping after receipt of ground control?

A. Under 50 Ac - 5 to 7 days / 50-200 Ac - 7 to 12 days.

Q. What is Digital Terrain Modeling (DTM)?

A. A Digital Terrain Model represents a three-dimensional (3-D) model of the earth's surface. A DTM is significantly improved by collecting additional "breaks and spots" (see next question/answer). (See mapping collection page)

Q. What are "breaks and spots"?

A. "Breaks" are horizontal (x,y) plan features (i.e. edge of road, curb, fence line, etc.) and ground terrain changes in slope (top, bottom, crown, etc.) collected with a vertical component (elevation-z). "Spots" are individual ground elevations at selected spots collected to supplement a more complete DTM. (see mapping collection page)

Q. How are plan features elevations collected?

A. Most of our planimetric features (roads, fences, poles, etc.) are collected at ground level to include elevation (z). Certain features are not collected at ground level such as buildings (roof corners), treelines and other similar elevated features. (see mapping collection page)

Q. What is a TIN?

Q. What is meant in mapping as "streaming" or "chasing" contours?

Q. What size should my targets be?

A. To decompress the zipped file, put the first disk of the set in the drive, type in A: or B: to switch to your floppy disk drive, then type in ETOPO "enter" to execute a batch file which will prompt you for your destination drive and tell you which disk to insert.

Q. Can E-TOPO use my CAD layering standards?

A. Yes.  Just send us a copy of your standards and we will put all symbols and lines on your layers.

Q. What digital formats can E-TOPO deliver mapping in?

A. DXF, DWG 10-14, MOSS., DGN, and various others.

Q. How do I open a DXF file in AutoCAD 14?

A. Start a new drawing (from scratch). Open the DXF file (dxfin).

Q. Can I get photographic imagery in digital format?

A. Yes, we are able to provide you with numerous different formats (tif, jpg, bmp, psd, etc.) see our scanning web page for more info.

Q. What is the difference between a digital scan and a Orthophoto?

A. A Orthophoto is scanned imagery that has been rectified from a terrain model.  A digital scan is unrectified.

Q. What resolutions of scanned imagery are available?

A. E-TOPO's scanner has an optical resolution of 600x1200 Dpi and a Interpolated resolution 9600 x 9600 Dpi. See our scanning web page.