[Mapserver-users] I have some landsat 7 data that I want to t ile : overlap + transparency

[Frank Warmerdam]

Kralidis,Tom [Burlington] wrote:
> Another comment: I'd be interested, as a separate exercise, how MapServer
> deals with overlapping images in a given layer.  What kind of algorithm is
> done between scenes which overlap?

Tom,

If the images are part of a single layer controlled by tileindex, then
all images intersecting the area of interest will be drawn in the order
they are returned by the tile index search.  Later ones will be drawn over
earlier ones.

Note that if you have MapServer shapefile spatial setup for your raster
tile index, the files may not be returned in the same order that they
appear in the tile index due to the way the "spatial index tree" is
walked.  If you want dependable ordering don't use a spatial index on
the tile index, and order them in the tile index in order of priority
(least to most).

Best regards,

-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent


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