I'm trying to render a pyro simulation generated with one of the sparse pyro FX shelf tools (specifically the campfire shelf preset) as a texture sheet for UE4.

It seems like it's impossible to generate normal information with the Labs ROP Texture Sheets node for this kind of sim. I've also tried with a sim generated by the Labs Fire Presets node. It seems to create normals (at least based on some other users examples on the forum) for certain sims, but usually ones that have a lot of smoke. I tried with a Fireball shelf sim and no normals would render still (I'm checking the N channel in Render View with the Sheets ROP's render_normal Mantra node)

In theory I guess it kind of makes sense considering a totally emissive volume shouldn't really interact with light (right?), but I can't figure out if I'm just missing something and normals should be generated (especially for the default Fireball shelf sim).

In general I'm getting slightly buggy behavior with the node, i.e. it doesn't always render RGB data depending on the fields of the SOP that the “Node to Render” is pointed to, takes quite a long time to render even a super low-res sequence, just isn't really a straightforward as I'd expected to generate texture sheets. An updated guide / workflow video would be really helpful for this node, especially if there was a clearer explanation of the workflow from Houdini into UE4's SubUV animation system. Attached is the file I was working with.

Thanks!

Because fire is emissive, the texture sheet ROP doesn't generate normals unless there's smoke. Generally normals are needed for lighting smoke. What would you like to use the normals for with the fire?

What is a really long time to render? I loaded up your scene and changed the voxel size to 0.02 and renders were taking about 10 - 15 seconds per frame.

Your setup is correct. The Node To Render path should point to the object level node, which yours does. You're not missing anything that an updated guide/video would provide.

One thing to note with the sparse setup is that it doesn't automatically generate a material the way the older shelf tools do. In fire_import, on the post_process node there's a button at the bottom of the parameters to create the material. This just means you can tweak the shader for the render but should be helpful.

Thanks for the reply Mike - it took some trial and error but I think I worked out the process for bringing flames into Unreal - I don't need normals, I was under the impression they'd still be generated from a fire sim just due to the presence of a density field - I was messing a bit with trying to change the field from density to heat or flame on the Advanced Settings tab but no real luck. With a regular smoke sim the Normals work fine

The thing that takes the most time is definitely the render step. Do you recommend rendering at full size or rendering the low-res? I've been rendering full-res and down-sampling but can't imagine the quality will be affected too much by rendering low-res from the start.

Most of the render time is spent on generating the ifd. The generating of the pixels is relatively quick. So render full res and downsample if you're happy with the result.
In the file you uploaded you have “override Camera Resolution” turned on so the images are only 128x128 which is fine too.