Adjusting Spatial Accuracy of Ortho Imagery in ArcGIS Desktop?

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09-22-2017 09:27 AM
LanceCole
MVP Regular Contributor

I have about 35 square miles of orthorectified, high resolution, aerial imagery that is broken down into 620 individual TIFF files. I have created a mosaic dataset of the imagery and I am working with ArcGIS 10.5 with all extensions.

I need to increase the accuracy of the imagery placement as the imagery was collected without the use of ground control and there are (x,y) errors of 1 to 3 feet across the area. I do have survey quality ground control points that are visible throughout the imagery. I also have a high accuracy DEM for the area created from LiDAR data, however, I really do not need to fully orthorectify the imagery again but rather just slightly spatially adjust the data.

Is there any ArcGIS tool available to correct this imagery?

I did look into using Bundle Block Adjustment but I am not sure if this is the best approach for the needed correction.

Also:

1) Would I need to create a full raster from the mosaic data to do the correction?  Each TIFF is about 100MB so that would be about 62GB for the whole area.

2) Typically, how many ground control points are utilized to correct an area this size.

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CodyBenkelman
Esri Regular Contributor

Lance

Unfortunately what you are seeking to do is not possible, at least not in a systematic and accurate manner.  

If you have a few areas with known errors, you could possibly use the Georeferencing tools in ArcGIS (and the "spline" adjustment with a lot of tie points) to "rubber sheet" your ortho and adjust some of the bad areas, but you would most likely introduce errors in other areas.  I would recommend against making the attempt.  

The proper solution would require access to the raw imagery and photogrammetric metadata (interior & exterior orientation) as well as your accurate DEM.  ArcGIS can do the orthorectification, but you'd need the source data.  Once it's been resampled and blended into an orthomosaic, you're stuck with the accuracy of what you have received.  

(Note this assumes you're not seeing something simple like a datum error that results in a systematic shift of all pixels in the same direction.  If that's the case, you can adjust with the Georeferencing tools in ArcGIS, but the proper solution would be a reprojection if you can identify the current datum)

If you have access to the source data and want to work through the orthorectification process, let us know.

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CodyBenkelman
Esri Regular Contributor

Lance

Unfortunately what you are seeking to do is not possible, at least not in a systematic and accurate manner.  

If you have a few areas with known errors, you could possibly use the Georeferencing tools in ArcGIS (and the "spline" adjustment with a lot of tie points) to "rubber sheet" your ortho and adjust some of the bad areas, but you would most likely introduce errors in other areas.  I would recommend against making the attempt.  

The proper solution would require access to the raw imagery and photogrammetric metadata (interior & exterior orientation) as well as your accurate DEM.  ArcGIS can do the orthorectification, but you'd need the source data.  Once it's been resampled and blended into an orthomosaic, you're stuck with the accuracy of what you have received.  

(Note this assumes you're not seeing something simple like a datum error that results in a systematic shift of all pixels in the same direction.  If that's the case, you can adjust with the Georeferencing tools in ArcGIS, but the proper solution would be a reprojection if you can identify the current datum)

If you have access to the source data and want to work through the orthorectification process, let us know.

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