Ascii format rendering

[Matthew Perry]

Salah,

On 2/23/06, salah jubeh <s_jubeh at yahoo.com> wrote:
> I have an ascii image the have , i have created this image by calculating
> the NDVI so the picxel values are from 0-1 also there are oixel has values
> -9999 which represent the No nodata_value .
>
> when i render thes image using mapserver it gives me just black images, i
> have checked this image with othe softwares it is correctly created .
>
> how can i fix this problem.

Two things to check:

1) Do the ascii raster extents match the extent of your mapfile?

2) Did you scale the image according to data range? Since your values
go from 0 to 1, you can use a processing directive in your layer to
scale the values in that range from black to white:

  PROCESSING "SCALE=0,1"

There's a good how-to on raster access that you might want to check out also:
http://mapserver.gis.umn.edu/docs/howto/raster_data

Best of luck,
--
Matt Perry
perrygeo at gmail.com
http://www.perrygeo.net