topic Re: Mosaic Datasets: Reprojection in Data Management Questions

Mosaic Datasets: Reprojection

LisaShertz — Tue, 21 Jun 2011 14:52:23 GMT

I have a largis-ish number (~2000) of tiles that I am putting into a mosaic dataset. They are currently in a different coordinate system than the rest of the data in our database. What is the best method of reprojection?

I know when you create the mosaic dataset you define a projection. Do I define this as the current projection or the projection that I want them to be in? Is that reprojecting the tiles? Is this causing the tiles to reproject as the end user calls them? I want the imagery to draw as quickly as possible for both desktop clients and internet applications.

Lisa Shertz
GIS Analyst
City of Longmont

Re: Mosaic Datasets: Reprojection

MelanieHarlow — Wed, 22 Jun 2011 18:37:30 GMT

Don't alter the prj of your tiles. ArcMap reprojects data in its display but web applications do not.

As you suggested, the projection you define for the mosaic dataset should be the projection you want to use when viewing the imagery. Not the projection of the source imagery.

If the spatial reference systems of the tiles and the mosaic dataset are based on different spheroids you may need to specify a specific geographic transformation. See Creating a mosaic dataset for more information.

Re: Mosaic Datasets: Reprojection

LisaShertz — Thu, 23 Jun 2011 15:42:45 GMT

Thanks, that was very helpful.

Lisa