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assistant pimp
07-22-2005, 04:54 PM
But then again it is.

Ok when you see images like this http://www.lightworks-user.com/image.php?img=aclass1k_640 I notice the hdri image in the bgrd. Yet the piece seems to fit in the scene and cast shadows and such. My question is how is this done? Do you have to painstakingly match the angle of the picture then photoshop the shadow? Or is there a way to hide a plane in there? Or am I trippin and the whole scene is actually modelled?

Also one other question. If I do a hdri render. Is there a way to hide the bgrd? BTW bgrd = background (the HTML in me shines thru sometimes)

Panikos
07-22-2005, 08:43 PM
You have the scene illuminated from an HDR surrounding ball, while you can have a modeled floor with a front projection texture. Of course radiosity and raytraced reflections are used.
The shadow is generated by Global illumination, not a light.

You can hide the surrounding HDR ball, by setting it to be Unseen by Camera.

assistant pimp
07-22-2005, 08:48 PM
Thanks for the reply.....So in the image I posted you think they actually modelled everything in the bgrd? It looked as if it was comp'ed in. I guess I need to learn more before I even ask this question. I am not sure how to ask what I am asking....lol.

Like if I have a photo and I want to comp in a object I made in LW, is that something that has to be done in Photoshop?

Panikos
07-22-2005, 10:14 PM
I think they modeled a flat floor, they texture and used frontprojection texture for it.
The scene was illuminated by a HDR textured ball

There are literally infinite ways to do things.
Its a matter of communicating well with the software and have a definite imagination of what you desire. Once you have these, such questions are answered by themselves.

gerardo
07-23-2005, 05:06 AM
But then again it is.

Ok when you see images like this http://www.lightworks-user.com/image.php?img=aclass1k_640 I notice the hdri image in the bgrd. Yet the piece seems to fit in the scene and cast shadows and such. My question is how is this done? Do you have to painstakingly match the angle of the picture then photoshop the shadow? Or is there a way to hide a plane in there? Or am I trippin and the whole scene is actually modelled?

Also one other question. If I do a hdri render. Is there a way to hide the bgrd? BTW bgrd = background (the HTML in me shines thru sometimes)

Front Projection can be useful like Panikos said (mainly with simple photographed backgrounds), however I think that this isn't the case.
That HDRI is in light probe format (angular map), what makes me think if that image was made with LW, the illumination should have been made with Imageworld and Background_Radiosity (if any trick hasn't been used to speed up the render). The bacground is the same HDRI transformed to Vertical_Cross format (Cubic Environment), the most appropriate format to take advantage of panoramic radiance maps for photogrammetry process of the distant scene or just as 3D background for the final render (as is the case of your example) :)



Gerardo

Panikos
07-23-2005, 05:18 AM
Gerardo, I guess you are right about the Vertical Cross format.
Even though it doesnt work in animation, especially when the 3d-app simulates a pinhole camera and the cheat is visible when you rotate the camera around you can easily detect the corners.

Imageworld is useful as long as your camera never sees the -Z view of the world, since Imageworld stretches the image badly. Personally I am a HDR-sphere-like rendering fan

:thumbsup:

gerardo
07-23-2005, 05:38 AM
Gerardo, I guess you are right about the Vertical Cross format.
Even though it doesnt work in animation, especially when the 3d-app simulates a pinhole camera and the cheat is visible when you rotate the camera around you can easily detect the corners.

If you use just a cube as background, I agree; but if you use it to make the photogrammetry process correctly, you won't have those problems :)

Imageworld is useful as long as your camera never sees the -Z view of the world, since Imageworld stretches the image badly. Personally I am a HDR-sphere-like rendering fan

:thumbsup:

Imageworld doesn't stretches the image badly. If you use a light_probe photographed and assembled correctly, you won't have those problems :)




Gerardo

Panikos
07-23-2005, 06:53 AM
:love:

http://www.univie.ac.at/Luftbildarchiv/wgv/intro.htm

Unfortunately such equipment is not accessible for everyone

For instance, you pay to use HDRShop 2.0 for a fixed period of time.

gerardo
07-23-2005, 07:13 AM
:love:

http://www.univie.ac.at/Luftbildarchiv/wgv/intro.htm

Unfortunately such equipment is not accessible for everyone

For instance, you pay to use HDRShop 2.0 for a fixed period of time.

Photogrammetry is not an equipment, is a technique; and as well as we can use a panocam (as SpheronVR) to obtain a panoramic radiance map, or simply to use a crome ball and HDRShop; in the same way there are cheap procedures for photogrammetry (mostly if we are talking of integrating CG elements on live action plates) :)



Gerardo

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07-23-2005, 07:13 AM
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