Datum Transformations: TIFFs vs SIDs?

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02-11-2014 07:58 AM
MichaelNesius
Occasional Contributor
Hi All,

I'm currently working with imagery collected in NAD 83 and NAD83 HARN.

When working with the original TIFF images, I can apply the datum transformation and everything lines up fine. However, when I try to do the same thing with the SID-ed versions of the images, the transformation doesn't make the images line up.

With the SIDs, the slivers/gaps between the images are persistent at scales 1:1000 and larger...the slivers will 'flicker' on and off while zooming between scales 1:1500 and 1:5000. I'm guessing this has something to do with the internal pyramids of the SIDs? Do I need to re-project the TIFFs and make SIDs from those?


Any guidance and/or suggestions on how to get the SIDs to line up would be greatly appreciated (I ultimately have to produce a mosaic dataset with the SIDs).

I attached a PDF of various screenshots.

Thanks for the help,
Mike
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MichaelNesius
Occasional Contributor
I figured it out.

There was an unconventional abbreviation of the HARN based projection in the TIFF's header information that didn't seem to migrate well to the SID's header, leading ArcMap to interpret it as a 'Custom' projection. The alignment issues seem to have arisen from truncated/rounded parameter values in this 'custom' projection being read from the SID's header, compared to the predefined NAD83_HARN projection paremeter being used with the TIFFs.

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MichaelNesius
Occasional Contributor
I figured it out.

There was an unconventional abbreviation of the HARN based projection in the TIFF's header information that didn't seem to migrate well to the SID's header, leading ArcMap to interpret it as a 'Custom' projection. The alignment issues seem to have arisen from truncated/rounded parameter values in this 'custom' projection being read from the SID's header, compared to the predefined NAD83_HARN projection paremeter being used with the TIFFs.
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