topic Re: No light behind camera when rendering in mental ray with wraparound lens in 3ds Max Shading, Lighting and Rendering Forum

No light behind camera when rendering in mental ray with wraparound lens

Anonymous — Sun, 08 Jan 2017 16:02:31 GMT

So I'm working on a 360 degree video as a final project in my 3D animation class. I can't install Vray so I instead opted for mental ray and using the wraparound camera lens. It works pretty well but my only problem is that the area to the back of the camera is very dark. I've attached the scene I'm trying to render and as you can see the area to the back of the ship (should be a door) is extremely dark and shadowy as is the sky (would appear as not having any stars)

I've seen someone with this same mental ray + wraparound setup on YouTube and they are not having this issue

Same thing happens when I use the panorama exporter.

Note: You can see the issue in the attachment alone but I recommend opening in a 360/panorama viewer

Re: No light behind camera when rendering in mental ray with wraparound lens

Francisco_Penaloza — Mon, 09 Jan 2017 21:31:45 GMT

Are you using Final Gather or Photon Mapping?

if you don't have lights in the back of your room that area should be darker than the rest of the room.

Re: No light behind camera when rendering in mental ray with wraparound lens

Anonymous — Mon, 09 Jan 2017 21:40:37 GMT

I don't have any lights down at all as, usually, the scene is pretty well lit (when not using wraparound) I'm also not that good with lights.

I didn't specifically set Final Gather or Photon Mapping, but while looking in my render settings it looks like Final Gather is enabled

Re: No light behind camera when rendering in mental ray with wraparound lens

Francisco_Penaloza — Mon, 09 Jan 2017 21:53:01 GMT

Mental Ray is is a physically based rendering, it can be adjusted to bend rules and do whatever you need, but by default it will follow physics rules, if there are no light, everything will be dark.

By default Final Gather will be on, if it won't have any light bounces, I would recommend to at leas put 4 bounces on final gather and see how your scene looks.

If you are not sure about lighting, or you don't have any plans in had I would use rectangular lights 2'x2' or 2'x4' and place them 6 to 8 Ft apart in any direction. This will give you an over all even lighting, then you can add more accent lights as need it.

How big is your scene??

I am imagining you have everything setup at real world scale correct?

Re: No light behind camera when rendering in mental ray with wraparound lens

Anonymous — Mon, 09 Jan 2017 22:31:46 GMT

I've rendered in Mental Ray without actually placing lights before, but I'll give the lights a shot.

I'm using proper scaling so I'm really just eyeballing it. The class I'm taking is a very beginner course so things like scaling and lights are things I haven't learned yet.

Re: No light behind camera when rendering in mental ray with wraparound lens

Anonymous — Mon, 09 Jan 2017 22:48:42 GMT

Here's the scene with final gathering + 4 bounces (the white spheres are untextured planets)

Re: No light behind camera when rendering in mental ray with wraparound lens

Francisco_Penaloza — Mon, 09 Jan 2017 22:53:04 GMT

I am trying to understand your problem.

So your idea is to see the outside stars???

those black areas are the windows??

how you placed those stars?? are they in a plane, sphere, on the environment map?? it is a 360 panorama photography?

Re: No light behind camera when rendering in mental ray with wraparound lens

Anonymous — Mon, 09 Jan 2017 23:47:30 GMT

I will try to explain this as clearly as possible.

I am working on a 360 degree panorama video

I am rendering in Mental Ray because I can't install Vray and I am using the Wraparound camera

lens to achieve the 360 degree effect.

When rendering a regular scene in Mental Ray (not 360 degree) the lighting is absolutely fine.

When rendering a 360 degree scene in Mental Ray the lighting is fine in the direction the camera was facing,

but in the opposite direction it is very dark.

The lighting should be equal on all sides when rendering 360 degree

I will attach 3 pictures to explain this a little better

The first picture is a screenshot from 3dsmax

The second picture is a 2d render from that scene

The last picture is a 360 degree render from that scene. If you look at the sky you'll see that it is bright

towards where the camera was pointing (see camera position in the first picture) and dark where the camera is NOT

pointing.

Why is this and how do I fix it?

Note: I switched from the space scene to this scene to make it a little more understandable.

Re: No light behind camera when rendering in mental ray with wraparound lens

Francisco_Penaloza — Tue, 10 Jan 2017 00:11:18 GMT

If you don't put any lights in your scene, 3D Max will render with a default light, this is not recommended.

Image below I placed a photometric light behind the camera.

on the image bellow I placed a omni light setup only for ambient lighting, with AO on the room material to read the shape,

otherwise will look flat like the image bellow.

Re: No light behind camera when rendering in mental ray with wraparound lens

Anonymous — Tue, 10 Jan 2017 23:43:19 GMT

Thanks! I guess I'll go and learn more about lights then.