I think I am in agreement as well.

Is there a list of Geotools SLD Vendor parameters?

Jesse

On 22-Jan-09, at 4:09 PM, Justin Deoliveira wrote:

> Sounds like a reasonable approach to me. What will the option look  
> like
> to the user? Will it be a vendor parameter in an SLD? Or what did you
> have in mind?
>
> Andrea Aime wrote:
>> Hi all,
>> I'm writing to build some consensus on how to handle a
>> compatibility breaking change.
>>
>> Years ago, way before my involvement in GeoServer, I
>> introduced a rendering optimization for lines. The
>> observation was that if the line width was less than
>> 1.5 pixels, setting it to 0 flat would make the rendering
>> quite a bit faster (30%+ if my memory serves me right)
>> and the visual result would have been the same.
>>
>> Now, at the time I was not using antialiasing, as it
>> made rendering times untolerable on my Athlon 700Mhz,
>> and I did not notice how that optimization affected
>> antialiased rendering.
>>
>> These days more than one people complains that they
>> cannot control the thickness of thin lines. No wonder,
>> it's the above optimization kicking in.
>> And with antialiasing rendering on, well, you can
>> tell a difference between line withs of 0.5, 1,
>> and 1.5 pixels (just to make an example).
>>
>> So, what can we do? Kicking off the optimization
>> the hard way does not seem like a good option to me.
>> People have been creating styles based on the current
>> behaviour, changing it would change the way maps
>> are rendered.
>> To give you some examples, here are maps that
>> have been rendered with the optimization on (the
>> current behaviour) and off (the proposed change).
>>
>> USA population:
>> default: http://www.flickr.com/photos/29313...@n03/3217765574/sizes/ 
>> o/
>> opt off: http://www.flickr.com/photos/29313...@n03/3217765474/sizes/ 
>> o/
>>
>> USA population, with hatch fills:
>> default: http://www.flickr.com/photos/29313...@n03/3216912511/sizes/ 
>> o/
>> opt off: http://www.flickr.com/photos/29313...@n03/3216912387/sizes/ 
>> o/
>>
>> Tasmania:
>> default: http://www.flickr.com/photos/29313...@n03/3217765504/sizes/ 
>> o/
>> opt off: http://www.flickr.com/photos/29313...@n03/3216912443/sizes/ 
>> o/
>>
>> As you can see the rendering changes, in some cases, significantly.
>> It's still possible to get back the old "thin line" rendering, you
>> just have to go and specify a thinner line with, such as 0.5, in the
>> SLD.
>>
>> What I'm proposing is to create an option that allows to toggle
>> the optimization on and off at the renderer level, and at the
>> SLDStyleFactory level (since this is where the optimization
>> really kicks in). For the 2.5.x series, we leave
>> the option on by default, so no change in rendering occurs
>> unless you tell the code otherwise.
>>
>> For the trunk series, I'd say that we should turn the
>> optimization off by default, but leave the toggle around for
>> one more release cycle, after which, we remove it completely.
>>
>> How does this sound?
>> Cheers
>> Andrea
>>
>
>
> -- 
> Justin Deoliveira
> OpenGeo - http://opengeo.org
> Enterprise support for open source geospatial.
>
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