Author Topic: Shadowmap problem  (Read 2832 times)

sach

    Reputation: 17
Shadowmap problem
« on: January 26, 2012, 06:56:10 pm »
January 26, 2012, 06:56:10 pm
Hi, i tried every setting of shadowmap but can't achieve good result, what's my problem.

Even tried Dept offset of materials.

Thanks

Sacha

Re: Shadowmap problem
« Reply #1 on: January 26, 2012, 08:39:43 pm »
January 26, 2012, 08:39:43 pm
I assume that you already tried adjusting the Shadowmap offset slider but in vain.

Can you zip + upload the scene files and the part of the building that exhibits the problem?

My email address is morten [at] act-3d.com.

Re: Shadowmap problem
« Reply #2 on: January 27, 2012, 06:35:16 pm »
January 27, 2012, 06:35:16 pm
Hi Sacha, thanks for forwarding the files to me.

The problem is caused by inaccurate shadows in Lumion.

Try extruding the concrete balconies further into the building, and let us know if that helps.

sach

    Reputation: 17
Re: Shadowmap problem
« Reply #3 on: January 28, 2012, 12:15:20 am »
January 28, 2012, 12:15:20 am
Nope, didn't help..........will this be fixed in a soon to be released patch.

Sacha

Re: Shadowmap problem
« Reply #4 on: January 30, 2012, 02:26:34 pm »
January 30, 2012, 02:26:34 pm
We're wrapping up a new update. Maybe we can allow for more controll over the shadow offset. Right now the slope offset is a fixed value. With a small slope value and max offset value the scene renders perfectly. The slope angle applies an offset based on the slope between the sun direction and the polygon. You can change your scene by simply changing the sun angle and the gaps disappear.

sach

    Reputation: 17
Re: Shadowmap problem
« Reply #5 on: January 30, 2012, 02:44:04 pm »
January 30, 2012, 02:44:04 pm
Yes, i can see but you'll agree it's like putting a plaster on a booboo.

I hope it'll get fixed in the next update

Thanks

Sacha

Re: Shadowmap problem
« Reply #6 on: January 30, 2012, 03:12:55 pm »
January 30, 2012, 03:12:55 pm
Yes, i can see but you'll agree it's like putting a plaster on a booboo.

I hope it'll get fixed in the next update

Thanks

Sacha

The problems stem from the way shadow maps are used to generate shadows. In essence a shadow map is just an images which shows the view from the light source but instead of the color it contains the distance to the light. To turn this into a shadow we simply test if a certain pixel is visible from the light.

The problem occurs in some cases when for example a surface strarts casting shadows upon itself. This is is because a shadow map only has pixels while the actual surface is a sloped polygon. The pixel is an oversimplification of the slope so in the final rendr you will see a triangle because one half of the pixel thinks it's visible while the other thinks it's not.

To remove this error we offset the pixel depth so the entire pixel contains the closest distance and not de distance in the center. This works perfectly because you won't see any false shadows anymore. In some cases, however, you can see gaps. The solution is to change the sun angle to reduce the slope, increase the shadow resolution to decrease the size of the pixels or you can mess around with the offset settings untill the problem disappears.

So actually there's no fix. We can however provide more control which will allow you to eliminate this type of artefact.

sach

    Reputation: 17
Re: Shadowmap problem
« Reply #7 on: January 30, 2012, 03:49:23 pm »
January 30, 2012, 03:49:23 pm
In "more control", do you mean more options of settings of the shadow.

Sacha

Re: Shadowmap problem
« Reply #8 on: January 31, 2012, 01:54:55 pm »
January 31, 2012, 01:54:55 pm
In "more control", do you mean more options of settings of the shadow.

Sacha

Yes. With an extra slider you will be able to tweak the shadow to eliminate artifacts.