Smoke is invisible in render

[fictionfxartist]

Hi all,

I was playing with rbd and added some smoke to a structure destruction , but i am not able to see the smoke in render even though it can be seen in viewport.

I know we have to cache it first using Dop I/O and i did that, It is visible but just 2% of actual smoke

I'll also be attaching the file

Please Help.

des_debris_v5.hipnc

[Feather]

Couple of things. 

1. What you see in the viewport is your source not a simulation.

2. When using a gas resize node, it will be looking to find your density field. It resizes around an existing density volume that is growing or shrinking. If there is no density present this results in the size of your bounds becoming a 1x1 cube at the origin. This is currently happening to your simulation. You need to either delay the frame at which it begins to resize your simulation to the frame at which your particle simulation actually exists at least for one frame OR better yet just don't start the smoke simulation until you know at least one particle will be present. 

3. Volume viz node requires that you specify the field it reads as density, yours is currently blank. 

4. Rendering the Pyro import node without a shader isn't going to look too fantastic, it needs a pyro shader. 

[fictionfxartist]

Thank you so much for your reply feather

If you see in my file i am first caching the smoke to disk from the Geometry node(Smoke), and then setting up a set up of Dop i/o and volume viz in another geometry node(Output), then i took this setup and connected it with Geometry1 node in Out directory where we usually render with mantra node. Now the process and caching here is a right way, right?

I delayed frame by 7(this is where my rbd sim starts) in resize container, is that okay?

Is there need to add a shader while caching? We can also add it before rendering right?

[Feather]

In your previous post you mentioned your smoke was rendering invisible. I thought you meant that you were referring to a mantra render in the render preview window. 

How you're caching the simulation is fine. As long as the Geo ROP is pointing to the import_pyrofields node not the import visualization node. 

As for the Gas Resize node, you tell me. if it resizes back to a 1x1x1 cube at the origin the answer is no, start frame 7 is incorrect.

The start frame needs to be whenever you first see particles coming from the pop simulation you're using to create the smoke source. If no particles are present, your density field is empty and so Gas Resize has no data to resize around. You need to start that smoke sim on the first frame that particles are emitted so that density exists for Gas Resize to capture.