topic Workflow to clip borders, compress, geo-reference, mosaic aerial photos? in Data Management Questions

Workflow to clip borders, compress, geo-reference, mosaic aerial photos?

JeffBaker — Wed, 21 Mar 2012 20:24:16 GMT

I have 96 aerial photos scanned from film that I need to geo-reference and mosaic. Each photo has a border and image numbers that need to be clipped for the mosaic. They were scanned at a high resolution in tiff with a file size of about 900 mb each. Ground resolution is 1 ft. The photos are along a river corridor and so the north orientation is different for each photo. I'm using ArcGIS Arcinfo service pack 4.

I'm wondering about compression or resampling, clipping the border, and the most efficient work flow to get this done. What would you do?

File storage is not really a problem but the images are slow to draw. Should I build pyramids and use original files, compress the files, before or after georeferencing?

Should I clip the borders before or after georeferencing? If I use a mosaic dataset, can footprints be used to address the borders, but do I have to set up a footprint for each photo or can they be batched? Will the different rotations of each photo make using footprints more challenging? Should I try clipping photos in photoshop before georeferencing? If so can they be batched?

Any advice will be be greatly appreciated. I'd rather do this right from the beginning rather than start over after going down the wrong road.

Thanks,
Jeff

Re: Workflow to clip borders, compress, geo-reference, mosaic aerial photos?

JeffreySwain — Thu, 22 Mar 2012 11:29:59 GMT

As long as the NoData area is homogenous(same value) then I would consider georeferencing all of the rasters, assembling a mosaic dataset and then use the Build Footprints to clean up the NoData area. Then you can use the mosaic dataset or export it as one raster as necessary.

I would not worry about the borders until you have the rasters in place, provided the Nodata area is as described above. There is not a quick way that I can think of to simply click a button and ArcMap will figure it out. Once you have the rasters georeferenced will be the biggest hurdle. Plus the rasters will display faster in the Mosaic Dataset provided you build the overviews.

Re: Workflow to clip borders, compress, geo-reference, mosaic aerial photos?

EjayLai — Mon, 06 May 2013 17:37:58 GMT

Great solution to the problem. I find it useful for the same problem that I am having. Thank you both!

Re: Workflow to clip borders, compress, geo-reference, mosaic aerial photos?

AnnKitowski — Wed, 24 Jun 2015 20:56:50 GMT

I have this same question. I have about 200 aerial photos that I need to scan and georeference. I was going to save them as jpgs with a dpi of 600. I tried tiff first, but the file sizes are so much bigger. Does it really matter what format the image is in? I checked out the border after scanning and it is not all one value (255). I was going to clip it in Photoshop first, but how much should be clipped? I thought that features in aerial photos became distorted as you get further away from the center. And with all the overlap, is it okay to clip a little more inside the border also? As Jeff said, it's better to do this correctly from the beginning.

Re: Workflow to clip borders, compress, geo-reference, mosaic aerial photos?

GregJohnson — Fri, 15 Jul 2022 14:58:22 GMT

I have a similar question, but now through ArcGIS Pro. We have just over 200 aerial photos. They have been scanned and georeferenced. The georeferenced images still have the marginalia items. I can clip each one since they represent 4 sections. Using the raster clip tool in ArcGIS Pro, the optional outputs are Create new layer or Save As which does not clearly specify the output format. My goal is to create a mosaic dataset with the clipped images. Anyone else converting old aerial images (pre-digital) and have some advice or recommendations?