cgcris Posted October 2, 2015 Share Posted October 2, 2015 Hi guys, Just started a new project and wondering what was the best way to render and comp an explosion. I would like to separate the flame from the smoke, to be able to offer some control at comp level. I've had a first go, in which I've turned densitiy on/off smoke (fireball shader) to separate both elements. However I am struggling to make them look right in Nuke. Some my questions are: 1) what's the best way of separating smoke and flame 2) How must they comped so they look integrated. Thanks in advance! Cris Quote Link to comment Share on other sites More sharing options...
Sierra62 Posted October 2, 2015 Share Posted October 2, 2015 in the extra image planes you seperate fire and smoke by adding these new feilds: fire_color fire_mask (set to float) smoke_color smoke_mask(set to float) Quote Link to comment Share on other sites More sharing options...
cgcris Posted October 2, 2015 Author Share Posted October 2, 2015 fire_color fire_mask (set to float) smoke_color smoke_mask(set to float) Awesome Cody, will do this next!!!! Quote Link to comment Share on other sites More sharing options...
Atom Posted January 15, 2016 Share Posted January 15, 2016 @Cody: I just tried your extra image plane suggestions with a pyro sim generated from debris particles. I have added the four fields to my EXR file and set the types to vector and float as mentioned. When I load the resulting render into Natron I can see that the channels do exist, but when I view them they are blank. I am new to this technique and Natron so it could be operator error but I wanted to ask if there was something else I needed to do in Houdini to populate these channels with data from the pyro sim? Quote Link to comment Share on other sites More sharing options...
fathom Posted January 15, 2016 Share Posted January 15, 2016 frankly, i prefer to simply separate things by lighting plane. flames are emission. smoke is volume. note, that when you export the emission you have use FULL OPACITY sampling or you'll get noise in your aov. i think the "direct emission" pulldown does this for you. Quote Link to comment Share on other sites More sharing options...
Atom Posted January 15, 2016 Share Posted January 15, 2016 I think I figured out why they are blank. The Billowy Smoke material does not have an export tab. The Fireball shader does and it specifies smoke_mask and fire_mask. @fathom: I'm not sure how to implement your suggestion. I do see a check box for Emission Color, but I don't see one for any volume. What is a lighting plane? Is it part of Extra Image Planes? Quote Link to comment Share on other sites More sharing options...
fathom Posted January 15, 2016 Share Posted January 15, 2016 the check mark system is a shortcut for extra image planes. i tend to use the actual "extra image planes" multiparm to output stuff since i have very direct control of the settings there. by lighting planes, i meant the "per component" style extra image planes you get from lighting. it kind of depends what's going on in your scene and what other rasters you're exporting. if you have an explosion by itself, i would do "direct lighting (per light)" and "direct emission". that will give you each light's individual contribution to your volume's look, plus the emissive component of the flames. smoke is (usually) just a "volume" component, so you also do "per light" and "per component" and then limit your components to just be "volume" (instead of the default "diffuse reflect coat refract volume"). you could probably also stuff in "direct_volume" for your vex variable and channel names instead of "direct_comp" and then just get the volume directly regardless of the components... lots of way to get the same stuff. Quote Link to comment Share on other sites More sharing options...
Atom Posted January 16, 2016 Share Posted January 16, 2016 Thanks for the info. I have been playing around with this all day. Do you happen to know what vex variable name I would use to get only the RED diffuse color into a float channel? I tried diffuse.r and diffuse[0] but my channel was empty. Quote Link to comment Share on other sites More sharing options...
fathom Posted January 16, 2016 Share Posted January 16, 2016 Thanks for the info. I have been playing around with this all day. Do you happen to know what vex variable name I would use to get only the RED diffuse color into a float channel? I tried diffuse.r and diffuse[0] but my channel was empty. you can't do that, as far as i know. if you only want a float exported to an image plane, you have to export a float from your shader. i tend to export everything as vectors (shader bind is vector and extra plane is vector), which i know is probably a bit wasteful, but if you work with nuke, float exports kind of suck. Quote Link to comment Share on other sites More sharing options...
Atom Posted January 16, 2016 Share Posted January 16, 2016 (edited) Thanks again for the info I think I am getting it. I can go into any shader and drop down a Bind Export. Do a VecToFloat and grab just a single channel. Then in the Extra Image Plane I can reference that export name and get only the float data. Which is how the fire_mask and smoke_mask seem to be made. Edited January 16, 2016 by Atom Quote Link to comment Share on other sites More sharing options...
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