topic Re: USGS NED Overlap in Data Management Questions

USGS NED Overlap

WayneLyngholm — Wed, 28 Sep 2011 20:53:54 GMT

Greetings,

I download 1/3 arc second and 1 arc second NED raster data from the USGS seamless server and the images have a slight overlap, they call it about six pixels. Anybody have a slick trick for removing that overlap from two adjacent images? Thanks! TB.

Re: USGS NED Overlap

EricRice — Thu, 29 Sep 2011 14:29:00 GMT

Greetings,

The first thing to come to mind was why do want to remove the pixels that overlap? In any case you have multiple options depending what you plan on doing. First (I think the most tedious) you can create polygons to define the area of the raster you want to keep, then use the polygon to clip the raster(s), essentially creating perfectly tiled raster datasets. This requires manually editing features... Optionally, you could mosaic the data together, then use the Split Raster tool to create the tiles. This doesn't require feature editing.

I personally would either mosaic the rasters together and choose an appropriate mosaic operator, like min, max, or mean, or I would put the elevation data in a mosiac dataset, thus preserving the original values in the data, but mosaicking on the fly (still using an appropriate mosaic operator).

You may find this 3 part series interesting.

Managing elevation data: Part 1: About elevation data

Managing elevation data: Part 2: Design and data management plan

Managing elevation data: Part 3: Workflow steps

Re: USGS NED Overlap

WayneLyngholm — Fri, 30 Sep 2011 21:15:04 GMT

Thank you Eric, the mosaic dataset was clearly the solution. This raster layer will overlay (at some level of transparency) a hillshade. The overlap was a visible seam in the transparency.