Fusion does not render caustics

[TrippyLighting]

This is more of an observation than anything.

What started as s simple modeling exercise to help out another user in this thread helped me discovering the limits of Fusion 360s render engnie, online as well as built in.

rendering the image of the ring shown belowe is not possible in Fusion 360, at least not in that quality.

1. I tried to load the HDR from the St. Peter's Basilica, Rome available here into Fusion 360 but it it comes only in lightprobe format. Fusion 360  needs it in longiture /latidude format. But, ok....

2. Modeling this seemingly simple object, while possible would be very tedious in Fusion 360, at least in the Sculpt environment. It took less than 10 minutes in Blender with the help of the array modifier. then export to .obj -> T-Spline in Fusion 360.

3. The most prevalent difference between the image rendered in Fusion 360 in the linked thread and the image below rendered with Indigo Renderer is the complete lack of refactive caustics, the "feathery" light patten under the ring, in the Fusion 360 rendering.

[michallach81]

Hi Peter, I would say that the main problem are the hdri maps that we have in Fusion. I've picked Skylight and resaults looks like that:

To be sure of my point I would have to find more maps and also try to insert some light source to my scene.

Michał

[michallach81 · Accepted solution]

You should also try Lagoa.

These are very quick shots:

and in attachments 19200x10800... for free (I just give it 1 hour to run, you can set much longer), all computed in cloud.

[michallach81]

File was too big to attached, here's a link:

https://we.tl/COhEZ3GZI5

[TrippyLighting]

Yes, the HDRI maps are part of the problem. I could not insert the St. Peter's lightprobe HDR into Fusion as it does not accept that format.

For interesting caustics you need small, high intensity light sources and that particular HDR has plenty of those.

I also noted, again, a differnece between the Fusion 360 internal renderer and the Fusion 360 Cloud renderer. The internal render engine produces some mild caustics where the cloud engine procuced absolutely none.

Indigo is more or less free for me. When that render engine went commercial many years ago they offered a full, lifetime version at a discounted price with all future releases free. At this point it's free for me 😉 It's also very accurate when compared with real life results as shown here on my blog.

However, I will certainly try out Lagoa as Iam looking for something more convenient to use right out of Fusion 360.

Here is a more drastic comparison. als using very small, hight intensity LED lightsources as used in my LED lamps: The first one is Fusion 360 internal, the second one is Indigo Renderer: