Using .map file as a raster layer source

Stephen Woodbridge woodbri at SWOODBRIDGE.COM
Thu Aug 25 17:17:21 EDT 2005


In a mapfile, if you have multiple overlaping layers then they all get 
drawn one over the next to build up the image.

How would your mapfile layer work? the same way?

So if I have a bunch of mapfiles representing the world and in same 
areas I have a city mapfiles that represent a city in detail and I have 
VMAP0 basemap mapfile layer, then it would draw the VMAP0 layer first 
and overlay it with the city layer, assuming the MIN/MAXSCALE of the 
city layer was on.

Is this your intent for this feature?

-Steve W.

Tamas Szekeres wrote:
> Frank,
> Certainly this solution should also work in the conventional way, when the
> DATA field contains the name of the mapfile. However that modification
> would also address the case when we have an overall map (like a Country)
> and a high number of detailed maps for a lower scale (cityes and
> villages), and if the user is zooming in an area the corresponding high
> detailed map should be drawn over the overall map. Tileindex is an option
> to prefilter the maps falling into the zooming area.
> Up to present I haven't found a built in alternative to achieve this
> issue, because for WMS, all of the hundreds of maps should be
> predownloaded and written into the filesystem though only one or two maps
> should be really drawn. Suppose that the detailed maps are with completely
> different layer structure, so layer level tileindexing does not work.
> However anyone could write a script to realize this, but I think that it
> is not practical to duplicate many of the functions already exist in the
> system.
> Using mapfile as a data source (like inline WMS) is a different approach
> which requires to realize many other features like selection of the
> layers, with much of work. In this case the "CONNECTIONTYPE MAPFILE"
> pseudo configuration would be syntactically more convenient.
> Tamas Szekeres
> On Thu, 25 Aug 2005 11:07:31 -0400, Frank Warmerdam <fwarmerdam at GMAIL.COM>
> wrote:
>>On 8/25/05, Sean Gillies <sgillies at> wrote:
>>>Neither of you say it, but to me this seems to be sorta like an inline
>>>WMS. I like the idea, and we should see about fitting it into the
>>>proposed new layer architecture.
>>It is indeed a bit like an inlined WMS, though it also, potentially,
>>is benefiting from the tile index.
>>However, I see it as orthagonal to the layer plugin proposal which
>>is really about making the layer *feature* access plugable.   It does
>>not address other aspects of layers, such as the Draw interface
>>which is still based on the layer TYPE.   In this case this is a
>>special case in the TYPE RASTER tileindex processing.
>>Actually, Tamas, does the mapfile name have to come from a
>>tileindex?  I don't see why it shouldn't be possible to have a single
>>mapfile listed in the DATA argument instead of having to use the
>>tileindex.  This would be in keeping with how other files work.
>>Best regards,
> ----
>>I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at
>>light and sound - activate the windows |
>>and watch the world go round - Rush    | Geospatial Programmer for Rent

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