Tell me more ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.
up vote 4 down vote favorite

Can someone please tell me what this purple anomaly is on the imagery that we just received. The only thing I have done processing wise is to build the pyramids when they first came into ArcMap. Other than that, I have not done anything. I also should add that the purple dissapears when zoomed in to an extent past 1:10000, and gets larger as you zoom out. Any help would be great. Thanksalt text

share|improve this question
Could it be something to do with the rgb colours?, and for anyone who needs clarification, it is a TIFF image. Thanks... – Andrew Dec 1 '10 at 21:50

2 Answers

up vote 4 down vote accepted

I would certainly go back to the original image and try rebuilding the pyramids. The fact that it disappears when zooming in to me means it's a pyramid issue. If it persists in ArcMap, do as @scw says, and try GDAL.

share|improve this answer
Thanks for that. Re-building the pyramids gave me a much cleaner image, and everything looks great. – Andrew Dec 2 '10 at 14:03
up vote 2 down vote

I can't specifically address why ArcGIS overviews are creating the purple block, but perhaps try creating overviews with GDAL on a copy of the file, and see if the artifact persists:

gdaladdo --config USE_RRD YES input.tif 2 4 8 16
share|improve this answer
I also tried this process, and it worked as well, so thanks!! – Andrew Dec 2 '10 at 14:04

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.