Iray: Is it possible to get a half spherical camera?

Diaspora

Right now, I'm only really interested in doing 180 degree animations, not 360, and so getting footage using the iray lens distortion type spherical leads to me wasting a lot of time/iterations/pixels etc because then in video editing I'm removing half the pixels to turn 360 footage into 180 footage.

But I looked at the other lens distortion types like inv_poly3 and inv_poly5, and then adjusted the lens distortion k sliders, I saw that I was starting to get an effect comparable to what a half spherical camera would look like. 

Any advice on how to figure out the exact precise settings necessary?

barbult

You might investigate Small World Camera. It has a 180 degree camera. It uses an unusual technique, where the camera focuses on a reflective ball, and the image rendered is the scene reflection in the reflective ball. There ares some significant downsides to this:

1. Everything is mirrored. Here is an example if a "normal render" and the same scene in the Small Camera 180 camera. Notice how the text house number on the red door is backwards. 
2. The reflective ball can cast shadows in the scene. You can see this near the bottom of the steps on the right side of the 180 render. I attached a screenshot of the ball and rectangle that are causing this shadow.

I've never tried this camera with animation.

charles

Small World Camera or inv_poy3  between .6 to .8 probably depending on distance or do it in post.

 

 

Diaspora

barbult said:

You might investigate Small World Camera. It has a 180 degree camera. It uses an unusual technique, where the camera focuses on a reflective ball, and the image rendered is the scene reflection in the reflective ball. There ares some significant downsides to this:

1. Everything is mirrored. Here is an example if a "normal render" and the same scene in the Small Camera 180 camera. Notice how the text house number on the red door is backwards. 
2. The reflective ball can cast shadows in the scene. You can see this near the bottom of the steps on the right side of the 180 render. I attached a screenshot of the ball and rectangle that are causing this shadow.

I've never tried this camera with animation.

The big downside I see of using a reflective ball is, in a physically accurate renderer like iray, this would mean that the GPU has to actually generate an image from processing all of the rays distorted through the reflective (refractive?) ball. Is this technique really expensive in terms of render time? 

Diaspora

So the solution I've come up with so far is that I have a camera set to spherical, and I take a dome that I made with create primitive and the geometry editor and I very carefully position it so that it's basically 'cupping' the rearward facing 180 degrees of the image, and then I set the material to just be completely black. What this ends up doing is making iray just render the back facing part of the image in solid black and that makes it way way faster than the alternative of rendering a full 360 image that I then trim the edges off of in post.

Theoretically though, the most perfect solution would be some kind of way just using the spherical camera as is but instructing DAZ/Iray to just somehow render only the middle 50%. In autodesk Maya this is called Render Region.

charles

If this is for still images you can use just about any image editor, photo-paint, photoshop to do this post really easy.

 

barbult

Diaspora said:

barbult said:

You might investigate Small World Camera. It has a 180 degree camera. It uses an unusual technique, where the camera focuses on a reflective ball, and the image rendered is the scene reflection in the reflective ball. There ares some significant downsides to this:

1. Everything is mirrored. Here is an example if a "normal render" and the same scene in the Small Camera 180 camera. Notice how the text house number on the red door is backwards. 
2. The reflective ball can cast shadows in the scene. You can see this near the bottom of the steps on the right side of the 180 render. I attached a screenshot of the ball and rectangle that are causing this shadow.

I've never tried this camera with animation.

The big downside I see of using a reflective ball is, in a physically accurate renderer like iray, this would mean that the GPU has to actually generate an image from processing all of the rays distorted through the reflective (refractive?) ball. Is this technique really expensive in terms of render time? 

I didn't time the render, but it was only a few minutes. It didn't seem any longer than the normal camera render. 

WendyLuvsCatz

you could use the section planes to hide the bits you don't want rendered 

Diaspora

WendyLuvsCatz said:

you could use the section planes to hide the bits you don't want rendered 

WOAH! now that is a feature I will find a lot of uses for! 

chris-2599934

barbult said:

1. Everything is mirrored. Here is an example if a "normal render" and the same scene in the Small Camera 180 camera. Notice how the text house number on the red door is backwards. 

Presumably you could fix this by simply mirroring the finished render back again in post.

barbult

chris-2599934 said:

barbult said:

1. Everything is mirrored. Here is an example if a "normal render" and the same scene in the Small Camera 180 camera. Notice how the text house number on the red door is backwards. 

Presumably you could fix this by simply mirroring the finished render back again in post.

Yes,that's pretty easy for single renders, but the OP is doing video. I suppose something like Premier could do mirroring possibly.

Diaspora

Yeah, if I went that route, adobe after effects can flip images extremely easily and quickly. It's really no problem at all.

But I have to give credit to Wendy, their advice about the iray section plane seems like the best option. Just to anyone reading this, make sure to select the section plane, go to Parameters>Section Pane> and set 'Clip Lights' to on and that way, light, shadows, and reflections from behind the camera will still be present in front of the camera.