Frequently Asked Questions

This page is designed to complement the Help page. If you ask us one of the questions on this page, you're likely to get an answer copy/pasted from here. If you have read this answer and are still unclear, please mention that you've looked at this page when you contact us so that we don't just give you the same answer again.

Azgcorr & Geocorrection

• When I geocorrect data, Azgcorr stops and complains that the flightline has a turn in it - how can I process my data?
• Is there any way to speed up geocorrecting my data or to reduce the file size of the geocorrected files?
• Why are my geocorrected files much bigger than my level 1 files?
• Why are my geocorrected files upside down? Do I need to manually rotate images to make north "up"?
• Why do my geocorrected Eagle/Hawk files have unexpectedly red/green/blue/yellow pixels?
• My azgcorr has expired, where can I get a new one?
• What is the azgcorr ASCII DEM format?
• Why does azgcorr say "DEM does not enclose the image" and then stop, and how do I fix it?
• My image data is in a .bil file not an HDF, how do I geocorrect it with azgcorr?

LiDAR Data

• What is the file format for my ASCII LiDAR data files?

Level 1 Data

• What are the bandwidths/band centres of my data?
• My data values are much larger than I was expecting. What units are the data in?

Datums and Projections

• If I load my ARSF data with a GPS dataset in a GIS, they don't match. Why not? Otherwise known as, why is British National Grid projection not where it should be, and what is OSTN02?
• What is the difference between an ellipsoid, a geoid, a datum and a projection