Matt,<br><br><div><span class="gmail_quote">On 9/15/05, <b class="gmail_sendername">Matt Garrish</b> <<a href="mailto:matthew.garrish@sympatico.ca">matthew.garrish@sympatico.ca</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Is there any way to mix two types of images, (one in decimal degrees
and one in metres?), or do I have to convert one or the other? If I do
have to convert (bearing in mind I am complete newbie), would gdalwarp
be the right tool? And can it be done when the tif file does not
contain coordinate system info?<br></blockquote></div><br>
You can convert them up front using gdalwarp but you have to know the
original projection. Even if the tiff's projection is not internally
defined, you can set it using the -s_srs option. The -t_srs option is
the output projection. Having all the datasets in the same coordinate
space as your mapfile output will be the fastest option, esp for large
datasets.<br>
<br>
Alternatively you can mix and match coordiante systems by defining a) a
PROJECTION object for your MAP which determines the output projection
and b) a PROJECTION object for each LAYER with a projection other than
the output projection. If you have huge datasets, reprojecting on the
fly like this will slow you down a bit but you can keep/maintain each
dataset in it's native coordinate system. <span class="q"></span><br>
<br>-- <br>Matt Perry<br><a href="mailto:perrygeo@gmail.com">perrygeo@gmail.com</a><br><a href="http://www.perrygeo.net">http://www.perrygeo.net</a>