Buffer query

[Stefanie Weykam]

> Hi list,
> I got inspired by Camden Daily's comments on buffer queries. But I can't
> get this strait.
>
> I am in a similar situation. I have to have my map in geographic
> coordinates as well. But my map covers a too big area, so I ought to
> reproject my query point and test layers to a metrical reference system
> before I do the queryByPoint at a determined buffer size.
>
> I have a point object and want to find all features within 500 Km
> distance. I expect to find 2 features within this radius. Just before the
> query is performed, I clone the point and the layer, reproject to UTM and
> set the tolerance value of my test layer to 500 and the units to Km.
>
> $projInObj = ms_newprojectionobj("init=epsg:4326");
> $projOutObj = ms_newprojectionobj("init=epsg:32632");
> $tmp_point = ms_newPointObj();
> $tmp_point->setXY($pt->x, $pt->y);             # clone the point
> $tmp_point->project($projInObj, $projOutObj);  # change projection of pnt
>
> $currentLayer = $map->getLayerByName("SPAMI");
> $tmp_layer = ms_newLayerObj($map, $currentLayer); # clone current layer
> $tmp_layer->setProjection("init=epsg:32632");  # change projection of lyr
> $tmp_layer->set(toleranceunits, MS_KILOMETERS);
> $tmp_layer->set(tolerance, 500);
> if (@$tmp_layer->queryByPoint($tmp_pt, MS_MULTIPLE , -1)==MS_SUCCESS)
> ....
> This does not return anything.
>
> Since Camden daily reported the same problem, I tried if I was lucky and
> find at least something in decimal degrees, but without considerable
> success.
> According to the MapFile Reference - 0 uses the tolerance value set in the
> map file, while any other value should use 'ground values'.
> So I tried other values, just for curiosity: 400 finds the nearest 5
> features - but this is too far for being a 400Km radius. At 500
> whatsoever-units all features are found and below 400 nothing is found....
> This makes me think that it's not the code that's wrong, but something
> related to Proj4. ???
>
> I'm using MS 4.2, Mapscript and PHP 4.3.7, on Win2000
> The Proj-files from MapServer work just fine, while those distributed by
> Maptools.org gave me some problems.
> I wonder if I should update or try to get the Mapscript proj-files working
> properly somehow?
>
> Thanks for your comments,
> Stefanie Weykam
> Ps: refering to another interesting comment a couple of days ago - Has
> anybody tried to draw a circle transforming the symbol coordinates from
> image to map coordinates so that the circle size matches the buffer
> distance of a query? Is this possible at all?