On Mon, Oct 16, 2017 at 1:23 PM, Erik H <[email protected]> wrote:
> I don't think we have much use for lines that are one pixel wide. > > I'm surprised at how difficult this is; isn't there some driver other than > AGG/PNG I could use? > In mapserver versions before 7.0 there is the GD driver. I use it for 8 bit GIFs. Not sure what it does with 24 images. Rich > > > > On Mon, Oct 16, 2017 at 2:50 PM, Lime, Steve D (MNIT) < > [email protected]> wrote: > >> So you really do need 24-bit output. I was looking back through the >> mailing list archives and it was mentioned back in 2012 that aliased output >> could be implemented for simple (1 pixel-wide) lines and polygons – so >> there is hope but I don’t believe (looking through the source) that Thomas >> ever fully implemented it. In mapagg.cpp there are ifdef’s for a symbol >> named AGG_ALIASED_ENABLED which makes me wonder if work was started. I >> tried setting that in mapagg.cpp but ran into compile errors and didn’t try >> and track those down. >> >> >> >> Of course you’d have to live with 1 pixel wide lines… >> >> >> >> Steve >> >> >> >> *From:* Erik H [mailto:[email protected]] >> *Sent:* Monday, October 16, 2017 1:15 PM >> *To:* Lime, Steve D (MNIT) <[email protected]> >> *Cc:* [email protected] >> *Subject:* Re: [mapserver-users] Draw roads WITHOUT anti-aliasing >> >> >> >> Thanks for your reply, but I should have mentioned that I have a LOT of >> different colors to be displayed, almost a million... >> >> >> >> I should also have mentioned that I've already tried to filter out the >> anti-aliased pixels by setting all alpha bytes to 255 and then assuming >> that all pixels that don't have alpha=255 in the PNG can be removed, but >> that assumption seems to be wrong. >> >> >> >> On Mon, Oct 16, 2017 at 2:00 PM, Lime, Steve D (MNIT) < >> [email protected]> wrote: >> >> Hmmm… I wonder if you just could use a pre-computed palette to control >> quantizing to 8 bits. You can supply a palette file (RGB or RGBA) and the >> MapServer will map 24/32-bit values to those in the palette. Format options >> are: >> >> >> >> FORMATOPTION "PALETTE_FORCE=TRUE" >> >> FORMATOPTION "PALETTE=palette.txt" >> >> >> >> This will definitely limit the colors in your output image to those you >> specify. The question is whether or not the anti-aliased colors will map to >> the right color and that will depend on your palette. I did write a simple >> test with a 5 color palette (black, white, red, green and blue) and it >> seems to work ok but that’s a very simple palette… Based on your >> application it might work though. >> >> >> >> - http://maps1.dnr.state.mn.us/cgi-bin/mapserv70?map=/usr/loca >> l/mapserver/apps/test/palette/test.map&mode=map (24-bit) >> >> - http://maps1.dnr.state.mn.us/cgi-bin/mapserv70?map=/usr/loca >> l/mapserver/apps/test/palette/test.map&mode=map&map.imagetype=png8 >> (8-bit w/5 colors) >> >> >> >> Steve >> >> >> >> *From:* mapserver-users [mailto:[email protected]] *On >> Behalf Of *Erik H >> *Sent:* Monday, October 16, 2017 10:58 AM >> *To:* [email protected] >> *Subject:* [mapserver-users] Draw roads WITHOUT anti-aliasing >> >> >> >> I'm running a tiling server that uses MapServer 7.0.4 to generate PNGs. >> >> >> >> My colleagues came up with an ingenious idea to animate traffic >> conditions that would require them to identify road segments based on their >> color. They asked me to generate tiles with a predetermined RGBA value per >> road segment. >> >> >> >> I configured a layer of type LINE, with a STYLE section containing 'COLOR >> [palette]' (palette being a field in the database query). Initially, I >> thought I was creating the images my colleagues needed, but it seems that >> the anti-aliasing causes some pixels to have colors other than the one I >> specified; this prevents us from identifying the road segments. >> >> >> >> We can live without anti-aliasing, but I was unable to turn it off; I >> tried both the AGG/PNG and GD/PNG drivers and messed with various >> FORMATOPTION identifiers, but nothing seemed to make any difference. >> >> >> >> Any suggestions? >> >> >> >> Thanks. >> >> >> > > > _______________________________________________ > mapserver-users mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/mapserver-users > -- Richard W. Greenwood, PLS www.greenwoodmap.com
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