Camera Body native to Rhino 7?

Alan_Farkas · January 29, 2021, 1:00am

Hey @pascal got a PD on the line over here, so quick Q: What is the NATIVE camera body (gate, etc) in Rhino 7? Is it just a 35 SLR?

John_Brock · January 29, 2021, 1:08am

Yes, 35mm

From “Lens Length” in the Help file:

Lens Length

When the projection is set to perspective, you can change the lens length of the camera. A “normal” lens length for a 35 mm camera is 43 to 50 mm.

Alan_Farkas · January 29, 2021, 1:10am

Thanks, @John_Brock - SO I can tell the Designer that I’m using a fairly TRUE 35mm SLR CAmera Body with whtever the lens is that he wants, correct?

I’m not talking about the LENS. I mean, the film gate, camera body type.

EDIT: Ah, assuming you meant the body, since I had asked that (Just gto confused with the ref to the Lens Length help file.) Thanks.

John_Brock · January 29, 2021, 3:15pm

I don’t know what you can tell him.

If you hold up a 35mm Camera with a 50-55mm lens on it, and look through it with one eye and leave both eyes open, the field of view (magnification) will be about the same in both eyes.
If it’s a 28mm lens, the camera will see a much wider field of view. It will feel like you’re Zoomed way back.
If it’s a 400mm lens, the camera will see a very narrow field of view and will seem like it’s Zoomed way in.

Alan_Farkas · January 29, 2021, 4:04pm

Thanks, I was just confirming that the native Rhino camera is based on a full-frame SLR Film Camera. Apologies if I made that any more confusing than it needed to be.

Helvetosaur · January 29, 2021, 4:41pm

The only thing that really applies in CAD is FOV - field of view.

A 50mm camera lens with a 36 x 24mm full 35mm frame (sensor or film) will have an included angle on the diagonal of 46.8°.

Rhino’s lens length setting will try to match this - but remember, you can vary the viewport aspect in Rhino - so the actual diagonal angle measurement will vary. If you make a viewport with an aspect ratio of exactly 1:1.5 like a 35mm frame, if you measure the camera frustum pyramid, you will get a diagonal angle that is identical: 46.8°.

Alan_Farkas · January 29, 2021, 4:53pm

Ah, thanks, that makes sense. Follow-up: Were I to use create a 16:9 aspect ratio viewport, and wanted to take images with a “50mm Lens”, is there a math equation I could use in order to find the closest Lens measurement to create that 50mm view?

Alternatively: Is there a way I could use the viewport/FOV/50mm Lens camera (as you’ve explained above) and have a “Safe Frame” at the 16:9 format?

I know @sampage (maybe he’s not on here anymore) made a tool for this, so maybe if you’re still on here, Sam, you can weigh in, too?

Helvetosaur · January 29, 2021, 5:04pm

Assuming you had a 16:9 film frame of 42.67mm x 24mm, you would need a lens length of about 56.6mm to have the same diagonal included angle of 46.8° (you can draw it in Rhino)

Alan_Farkas · January 29, 2021, 5:09pm

Ok, thanks. So, I should feel good about using a 56.6mm Lens in a 16:9 viewport, and telling the PD that if a camera were setup on-set in the same position, they’d get a similar framing?

SamPage · January 29, 2021, 6:22pm

Hi Alan,

Just seeing this. Rhino will emulate a full frame SLR camera, but the trick is that the minimum dimension for the film gate will always be 24mm. So if your viewport is 1.5:1, then the Rhino film gate will be 24mm x 36mm, which is a standard 35mm SLR. If you have a 16:9 viewport, and want to simulate what a 50mm would look like in that viewport, the Rhino film gate will be 24mm tall by 42.66mm wide ( 24 * 16 / 9 ). To get your lens multiplier, you then divide the gate width that Rhino is giving you (42.66mm) by the gate width you want (36mm), so that is a lens multiplier of 1.185. So, if you want a 50mm on a 16:9 viewport, it would be a 59.26mm lens.

Here is the latest of the camera lens script, it doesn’t have an option for SLR cameras, but maybe still of some use.

Sam
Cam_Lens_190204.zip (92.6 KB)

Alan_Farkas · January 29, 2021, 6:30pm

thanks, @Konrad

Alan_Farkas · January 29, 2021, 7:11pm

Thanks, @SamPage! Much appreciated. I’m going to get that updated script into my Rhino and play around.

Follow-ups below, if/when you have time, and again thank you for the amazing script, and your time!

Is the N35 camera body option (22mm film gate) closest to a “regular” digital 4K camera they’d be using on a 1 hour Drama 16:9 show these days?
This option that asks: Change Rhino lens to keep Normal35 lens constant? (LensChange=Yes/No)

SamPage · January 29, 2021, 7:40pm

I would think that most are still using Super 35 (in the script, that would be the DIN_Super35, with a gate of 24mm). It does get a little confusing because many digital cameras crop the gate to capture at different resolutions. Personally, if I’m unable to talk to camera dept about what camera they are planning on using, I just stick with the DIN Super 35, and tell people “this is a 21mm on a Super 35” and then be ready for a correction

The lens change option: Lets say you have already set a camera system, and you set a lens of 21mm. If you are change the viewport aspect ratio using the script’s Aspect command and you have Change Rhino lens to keep [camera system} lens constant=yes, the script will change the Rhino lens so that with the new viewport aspect ratio, the camera system you are trying to emulate will still have a 21mm lens. If you have Change Rhino lens=no, then the viewport before the aspect ratio change and after will have the same Rhino lens, which means that the camera system you are tying to emulate will have effective changed lens lengths.

Sam

davidcockey · January 29, 2021, 8:23pm

I conducted a quick experiment with objects in a perspective viewport. The objects were at different distances from the camera so the relative size and position of the objects depend on the camera position relative to the objects.

With the camera location fixed the relative size and position of the objects did not change when the viewport size or aspect ratio was changed. The relative size of the objects remained constant relative to the viewport size as the viewport size or aspect ratio was changed.

This shows that Rhino uses the viewport height when determining the field of view.

SamPage · January 29, 2021, 8:55pm

Unless is the viewport is taller than it is wide, at which point the width will determine the field of view. The minimum dimension is 24mm.

Alan_Farkas · January 30, 2021, 2:05am

Thanks, that’s great info!

nathanletwory · January 30, 2021, 7:13am

For what it is worth currently Cycles in Rhino uses these values:

github.com

mcneel/RhinoCycles/blob/rhino-7.x/Settings/DefaultEngineSettings.cs#L86


		static public float LightSamplingThreshold => 0.05f;
		static public bool SampleAllLights => true;
		static public bool SampleAllLightsIndirect => true;
		static public int Blades => 0;
		static public float BladesRotation => 0.0f;
		static public float ApertureRatio => 1.0f;
		static public float ApertureFactor => 0.1f;
		static public float SensorWidth => 32.0f;
		static public float SensorHeight => 18.0f;
		static public int TransparentMaxBounce => 32;
		static public int SssMethod => 44;
		static public bool ShowMaxPasses => true;
		static public int OpenClDeviceType => 4;
		static public int OpenClKernelType => 0;
		static public bool CPUSplitKernel => true;

(one can change those on the application level via Tools > Options > Advanced)

This may change to automatically being managed once RH-62538 Add SDK functions for camera sensor size has been resolved.

den.design · April 30, 2021, 7:52am

Hello Sam
I find your camera lens script really useful, are you likely to do a version for Rhino 7? I need to show views showing an accurate representation of film cameras and at the moment that doesn’t seem to be an option. Any help would be greatly appreciated,
Thank you