Soft Shadows with RayTracing by Howard Prince | « Previous Image | Last page in History | Next Image » |
Artist's Comments: Modelling/Render: Strata 3D Pro 3.9
Shadow Map: Ulead PhotoImpact XL
I'm sure this has to have been duscussed here before my time, but, far be it from me to NOT bring up old tricks that I just now am discovering on my own... :)
The Strata RayTracing rendering engine is very fast (compared to any current RT renderer on the market). Sometimes, the only reason I don't use it is because I want soft shadows; for that reason alone, I might have to endure render times of 300% and more from radiosity renders, just to get that desired effect - that's a big hit in render time, and if I am animating, almost upbearable.
Recently, I've learned about "shadow maps". These are maps that a light source uses to tell it where to cast light, and where not to.
The concept is, in essence. to "Fake" soft shadows by adding a little "soft" area around each object from the point of view of each light source (in this case, just one), to tell it to fade those hard RT edges away, gradually.
Other porgrams, such as Cinema 4D, Lightwave, Maya, etc.. generate thier own shadow maps to "soften" the edges of thier raytaced images; that is, they have a built in task that takes a "picture" of the scene from vatage point (view) of each light source, and darkens a little area around each object in that image to inhibit a little less light transmittance, fading to 100% light transmittance at its most outer edge. Not much, but just a little bit.. and this extra area outside the normal Raytraced shadow gives the shadows that particular light source makes, a "soft" edge.
The above scene was done by making just such a shadow map; here's how I did it:
1. Turned off the floor/ground plane, and removed all textures.
2. Opened up the spotlight light window
3. Final render qualaity of the light window at 200% size (raytrace)
4. Brought that render into my Image Editor (I use PhotoImapct)
5. Inverted the whole image (black became white, and white became black.. this is the format the Strata Gel information has to be in).
6. Painted a white space around the sphere; about 10 pixels, but not symmetrically - at the bottom of the sphere which is touching the ground plane, was only about 3 pixels, while the top was about 10.
7. Applied a gaussian blur to the sphere and the new white shadow and its surrunding area.
8. Exported to Strata.
9. Created a new Light Gel. One repetition, scale of "1" as well.
10. Applied the new Light Gel to the light, and tested.
11. Applied materials (glass to the shpere), and then set the photons in the render esoterica.
12. Rendered RT best, 3 sec.
That's a heck of a lot faster render than a RD render with photons. Yes, the time to make the shadow map has to be considered, but, if you are animating a camera around an object, this method can be a major time saver, allowing RT rendering at a great quality - quite comparable to Radiosity relative to soft shadows.
I rendered a 4 sec/60 frame animated camera around this sphere in less than two minutes, WITH photons, RT as discussed above, 9 pixel oversampling - it came out superbly slick.
If future versions of Strata can do internally as other 3D software currently does, which is to generate its' own Shadow Maps to give us soft shadows in Raytracing renders, it would truly allow us to benefit from the RT renderer in both speed and quality much more than currently is done.
Shadow Map: Ulead PhotoImpact XL
I'm sure this has to have been duscussed here before my time, but, far be it from me to NOT bring up old tricks that I just now am discovering on my own... :)
The Strata RayTracing rendering engine is very fast (compared to any current RT renderer on the market). Sometimes, the only reason I don't use it is because I want soft shadows; for that reason alone, I might have to endure render times of 300% and more from radiosity renders, just to get that desired effect - that's a big hit in render time, and if I am animating, almost upbearable.
Recently, I've learned about "shadow maps". These are maps that a light source uses to tell it where to cast light, and where not to.
The concept is, in essence. to "Fake" soft shadows by adding a little "soft" area around each object from the point of view of each light source (in this case, just one), to tell it to fade those hard RT edges away, gradually.
Other porgrams, such as Cinema 4D, Lightwave, Maya, etc.. generate thier own shadow maps to "soften" the edges of thier raytaced images; that is, they have a built in task that takes a "picture" of the scene from vatage point (view) of each light source, and darkens a little area around each object in that image to inhibit a little less light transmittance, fading to 100% light transmittance at its most outer edge. Not much, but just a little bit.. and this extra area outside the normal Raytraced shadow gives the shadows that particular light source makes, a "soft" edge.
The above scene was done by making just such a shadow map; here's how I did it:
1. Turned off the floor/ground plane, and removed all textures.
2. Opened up the spotlight light window
3. Final render qualaity of the light window at 200% size (raytrace)
4. Brought that render into my Image Editor (I use PhotoImapct)
5. Inverted the whole image (black became white, and white became black.. this is the format the Strata Gel information has to be in).
6. Painted a white space around the sphere; about 10 pixels, but not symmetrically - at the bottom of the sphere which is touching the ground plane, was only about 3 pixels, while the top was about 10.
7. Applied a gaussian blur to the sphere and the new white shadow and its surrunding area.
8. Exported to Strata.
9. Created a new Light Gel. One repetition, scale of "1" as well.
10. Applied the new Light Gel to the light, and tested.
11. Applied materials (glass to the shpere), and then set the photons in the render esoterica.
12. Rendered RT best, 3 sec.
That's a heck of a lot faster render than a RD render with photons. Yes, the time to make the shadow map has to be considered, but, if you are animating a camera around an object, this method can be a major time saver, allowing RT rendering at a great quality - quite comparable to Radiosity relative to soft shadows.
I rendered a 4 sec/60 frame animated camera around this sphere in less than two minutes, WITH photons, RT as discussed above, 9 pixel oversampling - it came out superbly slick.
If future versions of Strata can do internally as other 3D software currently does, which is to generate its' own Shadow Maps to give us soft shadows in Raytracing renders, it would truly allow us to benefit from the RT renderer in both speed and quality much more than currently is done.
