Generating raster overview to separate rasterset.

[Rahkonen Jukka]

Hi,

Best way I have found so far is to use Mapserver itself. For the whole rasterset it goes very easily by using tileindex as raster input, mapfile extents taken from the tileindex shapefile with ogrinfo,GeoTIFF as outputformat, some reasonable image size, and then asking for the whole layer from Mapserver. I think in your case it would be good to have one more zoom level in between, and for that you would need to add BBOX parameter to your request. When the site is covered by a suitable number of tiles they can be combined with another tileindex. I don't remember any problem in creating subsampled images this way, but of cause it takes some time and server timeout value must be set accordingly.

By the way, I suppose many Mapserver users would benefit if someone someday should make a simple semiautomatic application for performing this common task. It might for example show the tileindex shapefile as vector layer with full extents to start with, and then ask the user to give the number of rows and columns and size of the resulting images as inputs before splitting the raster layer to new tiles.

I have also used GDAL (by using GDAL .vrt virtual format as input) and commercial software (mosaic utility of ERDAS Imagine) but I prefer Mapserver because it is fast and not too tricky to use even when editing the BBOX parameters manually. For more automation I use to collect the Mapserver requests to batch file.

Regards,

-Jukka Rahkonen-



-----Alkuperäinen viesti-----
Lähettäjä: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] Puolesta Tormod Spigseth
Lähetetty: 24. heinäkuuta 2006 10:53
Vastaanottaja: MAPSERVER-USERS at LISTS.UMN.EDU
Aihe: [UMN_MAPSERVER-USERS] Generating raster overview to separate rasterset.

I have a 240GB aerial rasterset in 4000 tiles, any idea how i can generate separate raster sets for higher zoomlevels?

gdaladdo will still require mapserver to load 4000 files.

--
Tormod Spigseth
ByteX / Oxygen
bytex at o2.no