7 replies to this topic

[Laura Miles]

Hi Everyone,
I'm using ArcGIS 9.3 and need to rectify some historical aerial photos. When I use the "Rectify" command, I'm experiencing a loss of resolution. My boss doesn't want me to use Update Georeferencing, which doesn't cause this same resolution loss, but wants me to find a way around this. I believe it is caused by the resampling of the rotated pixels. Anyone have any suggestions or experience with this?
Thanks,
Laura

[s hubbard]

Hi Everyone,
I'm using ArcGIS 9.3 and need to rectify some historical aerial photos. When I use the "Rectify" command, I'm experiencing a loss of resolution. My boss doesn't want me to use Update Georeferencing, which doesn't cause this same resolution loss, but wants me to find a way around this. I believe it is caused by the resampling of the rotated pixels. Anyone have any suggestions or experience with this?
Thanks,
Laura

sounds weird (boss)
why can't you just fit to display, control point it, and transform?
are these scanned copies of the photos?
the loss of resolution may be from the rubbersheeting of the photo to fit your data >>

[Dustin Edge]

that is weird. Did your boss say why you should not use "Update Georeferencing"?

When you use the rectify option, it asks for the cell size, maybe the default value isn't small enough for the photos?

[Laura Miles]

Boss wants a "permanent" file...not sure why a georeferenced file is not "permanent" though. I have tried reducing cell size to 1/4 the default value, but it produces really huge files. Oh well sounds like that's the only solution. ESRI forums seem to indicate there is no real solution to this resolution loss, and Rectify is more for data which will be used in analysis, not photos displayed on a map. But, whatever the boss wants, right?

[Unit Seven]

Boss wants a "permanent" file...not sure why a georeferenced file is not "permanent" though. I have tried reducing cell size to 1/4 the default value, but it produces really huge files. Oh well sounds like that's the only solution. ESRI forums seem to indicate there is no real solution to this resolution loss, and Rectify is more for data which will be used in analysis, not photos displayed on a map. But, whatever the boss wants, right?

When you rectify are you using bicubic resampling?

[Laura Miles]

I have tried bicubic, nearest neighbour, and the other two. For some photos bicubic produced a better result, but strangely not for all...

[frax]

Maybe try to increase the resolution in the rectifying process?

[Laura Miles]

Yes, it seems that is the solution...unfortunately it produces a large file but there doesn't appear to be any way around that.