Hatches from DWF files renders poorly using AGG Render

[fare]

Hatches from DWF files renders poorly over AGG. It look to me that this is similar to ticket #1257. I'm providing proof and sample data(DWF is published from AutoCAD Map 2012). Images are served over WMS (EPSG:31276).

[fare]

Sample DWF file

[fare]

Sample DWG file

[fare]

Poor rendering

[fare]

How polytriangles looks

[zspitzer]

can you try this out with the 2.4 test release?

In my own testing I found the DWF handling been improved

[fare]

v2.4 test 2

[fare]

I tried version 2.4 test 2 and result is pretty much same.(see image)

[fare]

According to AGG sample page ​http://www.antigrain.com/demo/ and "gouraud" sample there are two methods that can be used to hide this kind of problem - dilating the polygons and/or changing the gamma-correction value.

I tried implementing the dilating polygons but didn't manage to remove artifacts. So I switched to gamma correction.

I'm proposing patch that is attached. Drawing polytriangles is separated to another method of AGGRenderer class. Basically method is copy of method that is used to draw polygons but before rendering occurs gamma value is set to low value (test showed that value between 0.3-0.5 gives satisfying results) and then restored to value 1.0 once rendering is done.

Lowering gamma value gives sharper outer edges(less anti-aliasing) but for me this is acceptable trade of.

[fare]

Sample of rednering with gamma value 0.3

[zspitzer]

Can you send a post about this patch to mapguide-internals and request a review?

[fare]

Review request sent.

Thanks for suggestion zspitzer.

[fare]

Proposed patch - fixed style

[waltweltonlair]

Fixed in trunk with r7896.