Arcmap Ortho Rectification Using NAIP.

An orthophoto, orthophotograph or orthoimage is an aerial photograph, geometrically corrected (“orthorectified”) such that the scale is uniform (Wikipedia)

ArcMap can be used to orto rectify aerial images to a NAIP imagery as a basemap.

I usually ortho rectify thermal imagery using this method, as we don’t have orientation information for the acquired thermal images.

These are the steps that I follow for creating ortho-mosaic from thermal imagery:-

  1. Extract tiffs (32 bit)  tiffs from the raw sequence file recorded by FLIR SC640 thermal camera.
  2. Convert 32bit floating tiffs to 16 bit unsigned integer format, as later I will use the rectified tiffs in PhotoMod for fine adjustments.
  3. Perform batch lens distortion correction on each frame.
  4. First download the desired base-map (NAIP Ortho imagery) from Geo Spatial Data Gateway or if I have a high resolution and more recent ortho-mosaic I can use that too.
  5. In case you have downloaded multiple tiles to cover the area of interest, you might want to mosaic the tiles together. I have discovered a quick way to mosaic tiles using gdal.
  6. Open the basemap (NAIP) image in ArcMap.
  7. Add a thermal image (one we corrected for lens distortion and converted to 16 bit) in ArcMap and
  8. Make sure Georeferencing toolbar is enabled, else enable it from customize>>toolbar menu.
  9. Watch the following video for detailed steps to create tie points and rectify image.[spacer height=”20px”]

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