[mapserver-dev] WMS exception for requests width height=1

[Martin Kofahl]

In that case the, MapServer should calculate with the distance from the
size from the center of a single pixel to border, I think. So 0.5. Changes
in https://github.com/mapserver/mapserver/pull/4629


2013/4/10 Worth Lutz <wal3 at mindspring.com>

>  If I understand correctly, it is because MapServer is based upon a cell
> size of center of pixel to center of pixel.****
>
> ** **
>
> With 1 pixel you have nothing. With 2 pixels you have 1 cell.****
>
> ** **
>
> Worth Lutz****
>  ------------------------------
>
> *From:* mapserver-dev-bounces at lists.osgeo.org [mailto:
> mapserver-dev-bounces at lists.osgeo.org] *On Behalf Of *Martin Kofahl
> *Sent:* Wednesday, April 10, 2013 2:40 PM
> *To:* MapServer Dev Mailing List
> *Subject:* [mapserver-dev] WMS exception for requests width height=1****
>
> ** **
>
> Hello,****
>
> currently, I see wms clients (qgis, arcgis 10) doing getmap requests with
> height=1. MapServer (6.2) throws an exception: ****
>
> ** **
>
> msDrawMap(): Image handling error. Unable to initialize image.****
>
> msCalculateScale(): General error message. Invalid image extent, minx=nan,
> miny=nan, maxx=nan, maxy=nan.****
>
> ** **
>
> The reason is in msAdjustExtent(), where the cell size is calculated
> using MS_CELLSIZE(miny,maxy,height), defined as ((max - min)/(d-1)).
> Formally, I don't see any reasons against 1 pixel requests. What are
> the reasons for "d-1"?****
>
> ** **
>
> Martin****
>   ------------------------------
>
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