Cast image from spotlight via a mirror object

Hello

As a total blender beginner I gave it a go as I want to showcase a device which casts an image via a mirror onto a half transparent glass which shows a simple user interface.

I created a spot light with a bitmap image which is thrown nicely onto an object…

Now I placed an object in the light path with reflectivity set to 1…but the image isn’t visible.

Is there a special trick in material settings or rendering settings to be able to cast images via mirrors?

thanks in advance
rick

It’s impossible with Cycles.

But you can use

  • FOSS: LuxCore (bidir), appleseed, Yafaray, POV-ray, Mitsuba…
  • Commercial: Indigo, Maxwell, Arion, VRay, RedShift, Renderman VCM/UPBP, Corona (SPPM or v3)*, Thea, Octane…
*experimental

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i.e. Render made with LuxCore Render 2 (bidirectional engine)

Wow…many thanks for the great pointers :slight_smile:

So far I only looked at complete 3D packages but not for render only software…

The last time I used render software only was the great BMRT package for SunOS 4.1.3, and that was some time ago :wink:

Do those renderer support a simple scene description like BMRT did in the past?

I liked the fact that the PRman like scene description was similar like PostScript…but as I want to learn anyway Blender as a side kick for Davinci Fusion …no worries (o;

I am more the textual than GUI guy…that’s shy I also prefer OpenScad for CSG :wink:

Oh…almost totally forgot…

Do any of thoser render software scale the casted image proportional to distance? This is where blender render also fails…

Best of all would be if it could also render a lense for simulating ultra short throw beamers…

do you need an optical simulation, or are you just looking to visualize a concept?

If you need an optical simulator, I’d recommend mitsuba. It’s not the most optimized, but it is a very powerful research engine.

If you are just trying to visualize something, then I’d recommend just sticking with cycles and cheating a bit. You can do some sneaky things with nodes and render layers, though it isn’t perfectly accurate.

Actually both…but I bookmarked all free render software before to test over the weekend…

One side is to visualize casted user interfaces on glass which also involves mirrors…and I hope aspherical shapes are not a problem…

When a render software could also simulate lenses and prism in a nice visual way then it it would be picture perfect…

It just lately popped into my mind a render software might be able to do so…maybe not as precise with specifying glass materials…but otoh who can afford Synopsys Code V which lease costs are 10k a year (o;

For lens design, you need specialized software to do so. Part of my job is designing projection systems that sometimes bounce off a single mirror. The light pyramid design stuff is easy and handled by CAD alone. Once we have the numbers, we sometimes render it out, although it is the finished result that matters, not how the image is portrayed in the mirror. Thus we cheat; image size in lens is too complex (paths from chip to lens would be handled/known by the lens designers), and even the size in mirror we don’t really care about (although CAD lets us verify mirror is big enough).

I assume keystoning is to be prevented. In that case, pretty much only throw and lens shift defines is all. You generally want to keep the mirror as small as practically possible (and thus, as close to the lens as possible). Big mirrors is a problem.

Just downloaded and installed from within blender-2.79b the zip luxcore render addon…

When I want to activate the luxcore render I get:

Traceback (most recent call last):
File “/usr/share/blender/scripts/modules/addon_utils.py”, line 331, in enable
mod = import(module_name)
File “/home/klingler/.config/blender/2.79/scripts/addons/BlendLuxCore/init.py”, line 13, in
from .bin import pyluxcore
ImportError: /home/klingler/.config/blender/2.79/scripts/addons/BlendLuxCore/bin/libembree.so.2: undefined symbol: _ZN3tbb10interface78internal15task_arena_base24internal_max_concurrencyEPKNS0_10task_arenaE

Okay…at least it runs under blender 2.79b on macOS 10.13.6 (o;

Octane is no option…installed the standalone version and rendered a sample scene from their website…
Uses heavily the GTX1060 GPU, which is good…but did reset the whole computer after few seconds…

Mitsuba seems rather old as it hasn’t had any updates since 2014…

Appleseed just seems to hang on macOS and Debian under blender…

And yafaray on blender macOS suddenly removes objects and camera…

This is weired…

Using now the LuxCore plugin…and render a simple green cube with matte material…nothing else besides camera and light…

Runs now for over 10 minutes with GPU and progress is still 0%

Hmm…seems it is not possible to use a bitmap as texture for a spot light with LuxCore renderer…just gives me a plain spot light…

Tried also with some different nodes settings…no luck…

Seems it is much simpler as I thought (o;

LuxCore renderer allows an image to be applied directly to a spot light, not as texture…
and even works via a mirror :wink:

Though dunno how to remove all the noise in the render output (o;

spotlight_with_image

Here is the render output as I am only allowed one picture per post (o;
Interesting to note that the mirror causes reflection to be seen inside the cases walls…though a spotlight shouldn’t do that…

This is very close to what I’m trying to accomplish: create a virtual studio for anamorphic art. I am shining the spotlight image on a cone with a mirror material, but it does not reflect the light from the mirror onto the plane below. So, how did you do this?

I am using Luxrender 2.4 with Blender 2.9. I tried both bdir and path modes with no success. Any idea what I might be missing?

Use Bidir engine.
Or, if set to “Path” enable “Light Tracing”. And further then, for SDS paths, also “PhotonGI Cache”.
spotlight_anamorph_reflection
spotlight_anamorph_reflection.blend (110.7 KB)

Brilliant! Thank you so much!!!