Hi, Never tried myself but for sure nodata value is not the way because it is not any continuous measure, it is just on/off. And opacity setting affects the whole layer as Jörg wrote.
I believe that the right way is to include alpha channel to the output colorrange. There are examples in the kernel density document http://mapserver.org/development/rfc/ms-rfc-108.html. In this example I suppose that the output color is total blue for the whole range from 0 to 32 but alpha value is growing from 0 to 255. style COLORRANGE "#0000ff00" "#0000ffff" DATARANGE 0 32 end I do not know how well and which clients support partial alpha values. -Jukka Rahkonen- Jörg Thomsen wrote: Hi Bob, this cannot work I think. A colorrange from 255 0 0 to 254 254 254 renders a map with many colors. In best case only data values at 300 will be rendered 254 254 254 (perhaps you can check that with a color-picker? perhaps a clean 254 254 254 is never reached). But I think you would like to have a layer where the smallest value is not transparent, the highest value is totally transparent and the values between are a bit transparent, right? I think you only can set the opacity for the whole layer. Jörg Am 03.06.2015 um 00:33 schrieb Basques, Bob (CI-StPaul): > All, > > My solution below turned out to not be correct either. It just ramps > down from RED to the color WHITE, no transparency. > > Here is the layer block I'm using that I'm trying to fade to a > transparent feature: > > MAP > > TRANSPARENT true > IMAGECOLOR 254 254 254 > > <more stuff> > > LAYER > METADATA > "ows_title" "bbox" > "gml_include_items" "all" > END > GROUP 'users' > NAME 'bbox' > STATUS ON > TYPE LINE > > > <DB connections stuff> > > > ## the following greabs a 5 min chunk of data (BBOX geoms from the > database from 28 hrs ago and assigns a seq and elapsed time column to > the result. > DATA "bbox from ( > > SELECT > row_number() over (order by accessed_at nulls last) as seq, > date_part('epoch', (now() - INTERVAL '28 hours' - > accessed_at)::interval) as elapsed, > id, accessed_at, bbox > FROM > layer_metrics > Where > accessed_at < (NOW() - INTERVAL '28 > hours') AND > accessed_at >= (NOW() - INTERVAL '28 > hours' - INTERVAL '5 minute') > > ) as subquery using unique id > using srid=200068" > > LABELITEM "elapsed" > > CLASS > #NAME "5 Minute Trail" > EXPRESSION ([elapsed] >= 0 AND [elapsed] < 300) ## 0-5min STYLE > OUTLINECOLOR 0 0 0 > OUTLINEWIDTH 1 > #COLOR 0 255 0 COLORRANGE 255 0 0 254 > 254 254 ##red to opaque (see IMAGECOLOR in the MAP block above) > DATARANGE 0 300 RANGEITEM "elapsed" > > END > END > END > END > > > bobb > > > >> On Jun 2, 2015, at 4:27 PM, Ben Madin <[email protected] >> <mailto:[email protected]>> wrote: >> >> Bob, >> >> Nice, I never knew that such a colorrange option existed (at least, I >> couldn't find it documented anywhere?) but I would have presumed >> maybe you could specify the colour using the alpha like any other colour? >> >>> COLORRANGE 255 0 0 255 255 255 255 0 ## red -> transparent >> >> >> >> Alternatively, if you had a common background colour, you could fade >> to that? >> >> cheers >> >> Ben >> >> >> >>> On 2015-06-03, at 04:48 , Basques, Bob (CI-StPaul) >>> <[email protected] <mailto:[email protected]>> wrote: >>> >>> All, >>> >>> Anyone know how to use a transparent color on one end of the >>> coloring option? >>> >>> COLORRANGE 255 0 0 ??? ??? ??? ## red -> transparent >>> >>> It there a RGB color to use for Transparency to fade to? I >>> basically want to fade a line based on age to nothing. >>> >>> Thanks >>> >>> bobb >>> >>> >>> >>> _______________________________________________ >>> mapserver-users mailing list >>> [email protected] >>> <mailto:[email protected]> >>> http://lists.osgeo.org/mailman/listinfo/mapserver-users >> >> >> -- >> >> Ben Madin >> >> t : +61 8 6102 5535 >> m : +61 448 887 220 >> e : [email protected] <mailto:[email protected]> >> >> AusVet Animal Health Services >> Western Australia >> >> AusVet's website: http://www.ausvet.com.au >> >> This transmission is for the intended addressee only and is >> confidential information. If you have received this transmission in >> error, please delete it and notify the sender. The contents of this >> email are the opinion of the writer only and are not endorsed by >> AusVet Animal Health Services unless expressly stated otherwise. >> Although AusVet uses virus scanning software we do not accept >> liability for viruses or similar in any attachments. Thanks for reading. >> > > > > _______________________________________________ > mapserver-users mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/mapserver-users > _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
