Mosaic Datasets: Reprojection

[LisaShertz]

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

[MelanieHarlow]

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.

[LisaShertz]

Thanks, that was very helpful.

Lisa