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benfirehose
07-09-2002, 04:15 PM
Just started using Softimage for school. Now don't get me wrong, it's a great program. But the default lighting is like something out of a horror movie. Is there a way to do soft shadows an easy way. I've tried some of the Final gathering and Global Illumintion tutorials on edharris.com and 3dbuzz.com and they just don't do the trick. maybe I'm looking in the wrong place, so...PLEASE HELP ME OUT!!

rotaryman
07-09-2002, 04:56 PM
Did you try playing with the Umbra settings on shadow?? if that doesn't do the trick then convert the light to an area light that should do the trick.

Good Times!

allawy
07-09-2002, 05:25 PM
Hi;

I'm new to XSI too, VERY new to 3D world tools too :), anyway, yes, there is a way but unfortunatily I think I have not master it very well yet, but it works!

Now from my little experience I know that soft shadow come only with area lights, this is why you have to pick point or spot light, go to it's properties sheet, and choose Area tab from there, activate the area checkbox and you have one.

now there are other factors you have to play around with, for the smaple here I choosed a sphere, 10 for smapleing and 60 scale for x,y,and z.

This is it, it take allot of time to render (for just a shaow), I'm not sure if other pacakges do this simpler than this.

now if I saved your life, I expect similar thing from you in the future :)

Regards

allawy
07-09-2002, 05:28 PM
OOOOPS, I forgot to say that you have to activate the shadow form the light sheet too, and yes paly with Umbra to get some degree of darkness with the light.

I think this hsould have been simpler :hmm:

benfirehose
07-09-2002, 06:14 PM
THANKS GUYS, it worked. Pretty simple too, you don't need the final gathering or global illumintion to pull it off either. I'll be sure to have somthing posted for your viewing pleasure in no time.

Vic3k
07-09-2002, 07:33 PM
the other way is to go to your light property and select bitmap shadows. shadows on the light have to be enebled for that. it works on all lgiths except for directional one. but with directional it actually works too but there is a big limit to the softness. you can only see a slight softness only if yyou zoom in up close.

bitmap resolution is hwo big the file will be.
sampling increased the accuracy
softness makes it more soft.

so for very soft shaddow use a point light, bitmap res to like 64, softness to 0.5, and sampling to about 32.

play around with settings, i don't ahve xsi open right now to tell exactly.

allawy
07-09-2002, 08:27 PM
I tried this, it did not work, please can you post details? I think it can be faster (simply I used Cinema 4D and it give soft shadow with much much shorter time), I'm not comparing any packages here, but we have to have some resonable soft shadow that don't take too much render time, regardless of my hardware Cinema 4D gave me this soft shadow in less time than XSI for the same simple scene.

Please help us :)

allawy
07-09-2002, 08:39 PM
oh my God! I'm so sorry, it worked, now

Res. 64
soft. 0.1
sample 60

I'm so sorry, silly me, did not check the Shadow map checkBox at the reder options.

Thanks allot and it's fast! I mean faster than the way I posted

THANKS!

Vic3k
07-09-2002, 09:44 PM
welcome :)
i said to enable bitmap shadows (which are called shadow maps in xsi) so that's the part you missed and i told wrong. it's so hard to come up with names if you don't have software infront of you :surprised

geoath
07-10-2002, 02:21 AM
hello to everybody!

to simulate (or "fake") area lights it's better to use more than one spotlight with shadow maps...
Area lights produce very natural shadows, that means soft shadows that get more diffused away from the object..the problem is that to have good results the settings require long render times, which can be a problem when u don't make a still image but have to render an animation with big resolution and many frames.
while shadow maps can produce shadows with no hard edges they can't produce that "diffuse" effect..they simply blur the whole shadow instead of starting focused and get diffused with distance.
a good solution is to duplicate some times the spotlights, divide the intesity of each light with the number of copies u made and place each light slight apart from the other ones... this way the shadow near the object will be more focused and become diffused away from it.
one last tip is avoid to use point lights with shadow maps..they take longer to render and also require more memory.

best regards
george

geoath
07-10-2002, 02:54 AM
a simple example:
on the left i used one light with shadow maps while on the right
i used 4 lights with same shadow map settings.

rotaryman
07-12-2002, 01:49 AM
so true geoath!
As a matter of fact that is how all the big houses do there lighting solutions. Jeremy Birn did a guest lecture at my school yesterday on the topic of (what else) lighting and rendering. It seems that most of the major houses don't even use radiosity, Final Gathering or GI, but rather simulate it all with the use of carefully place spotlights, and spotlight grids. The use of Radiosity and so forth fall into the hands of hobbyist rather than professional studio houses. However as time goes by and computer are faster, we'll see all these lighting features adapted to major house's pipelines.

But for the most part it is good to know how to light with spots, you can get a render that looks like GI or FG but renders in a fraction of the time.

Good Times!

HapZungLam
07-15-2002, 03:44 PM
Maybe it is a very stupid question.

What is a shadow map? what does it do, and how do i create it?

Atyss
07-15-2002, 03:57 PM
Originally posted by HapZungLam
What is a shadow map? what does it do, and how do i create it?

A shadow is a fake shadow. It's a bitmap map (like a texture) that is created during rendering and applied on top of the scene to fake penumbra.

At first this map is like a raytraced shadow, for instance sharp edges. But with the input of the user, the contours are evenly blurred.


To apply a shadow map, select your light, and go in the Shadow Map tab, check Enable Shadow Map.

The Resolution is the the resolution in pixel, or the amount of information in the map file. As a rule of thumb, in mental ray you should always use a resolution equal or superior than the width size of your rendering. Ex: NTSC is 720. If, after rendering, there are still squares, crank it up to higher resolution. It can goes to 2048!

The Softness is the width of the blur area.

The Samples is the amount of samples to be taken during the comptutation. Again, as a rule of thumb, you should always put at least the double of the Softness value. A minimum value would be of 10.


To see the shadow maps you must enable them in the Render Region and Render Options.


Hope this helps
Salutations - Cheers
Bernard Lebel

HapZungLam
07-15-2002, 06:02 PM
So a shadow map is auto generated by soft. not something we create by our own?

is it anytime when i enable Area light. I have to enable shadow map as well to get a soft shadow?

Atyss
07-15-2002, 06:03 PM
Exactly.



Bernard Lebel

geoath
07-15-2002, 11:42 PM
area lights don't need shadow maps to create soft shadows..if u try to activate shadow maps then area lights is automatically deactivated.
george

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