Status of AGG support?

[Stephen Woodbridge]

Hi Zak,

Thank you and the others for all the responses. I got it working this 
morning:

http://imaptools.com/agg-test.html

I have a few questions and observations:

The OL app above has two base layers. Both use the same mapfile, except 
one supports AGG and is using 5.0 and the other is using 4.10.

1) Notice the white lines in the water boarding some of the polygons. 
What is causing that? How do you get rid of these?

2) If you switch between 4.10 and 5.0 AGG base layers notice that the 
road widths change. What is causing this? I assume this is the same 
issue as the polygons above.

3) If you zoom in to 15K scale of closer so street names are displayed 
the text looks really bad on text ALIGN FOLLOW labels. And the text is 
much bolder and blacker than the 4.10 example.

more below ...

Zak James wrote:
> Steve,
> 
> In our testing, the AGG renderer is about 10% faster than GD over a
> variety of conditions. One caveat is that the sub-pixel positioning of
> vertices (which greatly improves the appearance of features) can cause
> far longer rendering times if suitable overview data aren't available
> for a given scale. We discussed but did not implement strategies for
> mitigating this problem. 

I think that discussion should get added to the RFC. If I wanted to 
provide my own overview data what are we talking about. Just having 
generalized data? Any rule of thumb on when you need to provide this?

> Another issue is that the antialiasing tends
> to cause larger image file sizes.

There really is not much that you can do about this. It will impact on 
bandwidth and tile repository sizes.

-Steve

> zak
> 
> On 7/3/07, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
>> Paul, Steve,
>>
>> A few questions:
>>
>> 1) could one of you do a short post on what if anything needs to be done
>> to use AGG other than install the libs and select some ./configure 
>> options.
>>
>> 2) Any sense on how this compares speed wise to the GD implementation.
>>
>> 3) is what is in the trunk all that 5.0 will see or is there some
>> additional work that is planed to be implemented.
>>
>> I would like to give it a try.
>>
>> -Steve W
>>
>> Paul Spencer wrote:
>> > The other thing that I am very keen to have is text rendered/placed
>> > using AGG.  Not sure if it will be done for 5.0 though.
>> >
>> > Cheers
>> >
>> > Paul
>> >
>> > On 3-Jul-07, at 1:25 PM, Steve Lime wrote:
>> >
>> >> Hi Tom: AGG support is in the codebase for 5.0. I still owe an RFC to
>> >> explain what was
>> >> done although the addition of AGG doesn't affect any other portions of
>> >> MapServer. It's
>> >> a big user feature though. I recently got a big time sink off my plate
>> >> and will work that up
>> >> ASAP.
>> >>
>> >> The support is relatively complete. The guys from DM Solutions can
>> >> probably comment
>> >> further as they've been using it the most. The AGG vs. GD images DM
>> >> has supplied are
>> >> very nice. The quality difference is noticeable with roads in 
>> particular.
>> >>
>> >> The only missing capability that I am aware of has to do with PIXMAP
>> >> symbols that contain
>> >> an alpha channel. There is a fundamental difference in how AGG and GD
>> >> handle alpha
>> >> blending (GD is flat out backwards).  We use GD to manage the pixel
>> >> buffer that AGG is
>> >> rendering into so that becomes a problem. I'll go into options in the
>> >> RFC.
>> >>
>> >> Anyway, other than that the support seems to be working nicely is
>> >> worth trying.
>> >>
>> >> Steve
>> >>
>> >>>>> On 7/1/2007 at 10:08 PM, in message
>> >> <7b5b710d0707012008i59c41e8bq8e0ef4d8022f40f8 at mail.gmail.com>, Tom 
>> Beard
>> >> <tom at PROJECTX.CO.NZ> wrote:
>> >>> Hi there,
>> >>>
>> >>> This is my first time posting here, and I hope this is the right
>> >>> forum to
>> >>> ask this question.
>> >>>
>> >>> I was wondering what the status of AGG support was for the 5.0
>> >>> release. On
>> >>> searching the archives, the most recent reference I could find was 
>> the
>> >>> minutes from the May 22 IRC meeting that said that there would be 
>> an RFC
>> >>> freeze on June 15, and that an RFC for AGG was "forthcoming". Did AGG
>> >>> support make it into that freeze? Is it listed somewhere online?
>> >>>
>> >>> I'd also be interested to know if there is a version currently in
>> >>> Subversion
>> >>> that includes AGG sub-pixel rendering and that works well enough to
>> >>> have a
>> >>> go at compiling on Windows.
>> >>>
>> >>> Regards,
>> >>>             Tom Beard
>> >
>> > +-----------------------------------------------------------------+
>> > |Paul Spencer                          pspencer at dmsolutions.ca    |
>> > +-----------------------------------------------------------------+
>> > |Chief Technology Officer                                         |
>> > |DM Solutions Group Inc                http://www.dmsolutions.ca/ |
>> > +-----------------------------------------------------------------+
>>
> 
>