I think your "halos" are blacks that are not pure black. Not 0/0/0, just close. This is a compression artifact. I think the same thing also happens with jp2 CCMs. The NAIP CCMs/or County Compressed Mosaics were never meant to be mosaicked together like this. They are a deliverable at the county level, not the state.
MapServer as far as I know will only do 0/0/0 and does not have a feature to make that fuzzy. You may have seen page, written some time ago, that speaks to this problem - http://sites.google.com/site/bpederse/caliwms The vertical and horizontal banding in the California case is related but diff from the halo effect. That is because with the large counties are cut into smaller sids in order to keep file sizes under control. That in combination with re-projecting the data causes issues with no-data areas. On Fri, Sep 17, 2010 at 11:28 PM, Gregor at HostGIS <gre...@hostgis.com> wrote: > Hey guys. > > I have some NAIP imagery in MrSID format. It displays, but the black area > where counties meet is really ugly. The MrSIDs are 3 one-byte bands: R/G/B > The bands do not specify a NODATA but I figure that 0/0/0 (all black) may be > usable as a NODATA value, via a PROCESSING directive. > > It works nicely, suppressing the black halos and making the almost-seamless > effect where the counties intersect. BUT... it only does so if I don't show > all 3 bands. If I specify any combination of BAND directives, I get a > greyscale image (of course) and the NODATA works (black halos are gone, so > counties are near seamless). > PROCESSING "NODATA=0" > PROCESSING "BANDS="1,2" > #PROCESSING "BANDS="3" > #PROCESSING "BANDS="1,3" > > But, if I do not specify the BAND or if I specify all 3 bands, I get the > black halos as if the NODATA were not specified. What gives? Is there > something special I must do to have the NODATA take effect for 3 or more > bands? > > -- > HostGIS, Open Source solutions for the global GIS community > Greg Allensworth - SysAdmin, Programmer, GIS Person, Security > Network+ Server+ A+ Security+ Linux+ > PHP PostgreSQL MySQL DHTML/JavaScript/AJAX > > "No one cares if you can back up — only if you can recover." > _______________________________________________ > mapserver-users mailing list > mapserver-users@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/mapserver-users > _______________________________________________ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users