Opacity in Fire

Forums Houdini Indie and Apprentice Opacity in Fire

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Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Nov. 26, 2013 4:40 p.m.

hi
i have problem in houdini when use pyro fx.
i see create custom pyro fx from digital tutors but i don't get answer my question.
my question is: how you can control opacity of the Flame?
for example how can i create this fire:http://www.youtube.com/watch?v=OPN2UPD_v3o [youtube.com]
when i create sphere and add Flame on that , flame is very chromatic and seems fire is painting!!!
i reduce brightness of the fire in shading tab but still i get chromatic Flame
please help me how can i create transparent fire like maya flame example and like above video.
thanks.


Sadjad Rabiee: Member; 1391 posts; Joined: Dec. 2010; Offline

Nov. 27, 2013 7:08 a.m.

You should use ramp parameters in the Pyro shader (instead opacity) to make more realistic fire !

check attached project and render it at frame 65

Attachments:
JK_PyroFire.hip (1.3 MB)

https://www.youtube.com/c/sadjadrabiee [www.youtube.com]
Rabiee.Sadjad@Gmail.Com


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Nov. 29, 2013 1:48 p.m.

1_please explain for me how did you create this fire?
just change field shape ramp for fire in material tab?
2_how can i render this fire in Mplay with alfred and renderman because when i create camera and add prman node for render , houdini console say can not find procedure of prman!
please help.
thanks.


Sadjad Rabiee: Member; 1391 posts; Joined: Dec. 2010; Offline

Nov. 29, 2013 2:40 p.m.

Yes ,I just use ramp parameter for this project.
To make good fire with sharpen edges ,Just set last point of the ramp to zero.

You can achieve perfect fire with ramp parameters like FumeFX (even better than it !)

I'm sorry ,I didn't work with Render Man ,But why you wanna use it ?

Mantra is faster and better rendering engine for volumetric phenomenon. :?

https://www.youtube.com/c/sadjadrabiee [www.youtube.com]
Rabiee.Sadjad@Gmail.Com


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Nov. 29, 2013 5:11 p.m.

thanks for your help
i decide to use renderman because i heard many thing about this engine for render and i being curious because it's not work in houdini.
thanks.


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

Nov. 29, 2013 5:35 p.m.

NimaNolan
thanks for your help
i decide to use renderman because i heard many thing about this engine for render and i being curious because it's not work in houdini.
thanks.

Renderman has to be purchased separately, have you done that? I'm not sure if Renderman can be used in Apprentice version too.


Sadjad Rabiee: Member; 1391 posts; Joined: Dec. 2010; Offline

Dec. 2, 2013 4:46 a.m.

Yes ,You should install renderman seperatly ,But try render your volumetric effects via Mantra and render others in the RM !

I think Rendering volumetric phenomenon with Motion Blur , Volume and Soft Shadows , Sampling(without noise and flicker) and … in the Mantra are greatest and faster than RM .

Also too many big companies use Mantra for volumetrics instead RM. 8)

https://www.youtube.com/c/sadjadrabiee [www.youtube.com]
Rabiee.Sadjad@Gmail.Com


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Dec. 8, 2013 5:19 a.m.

mental ray also need to buy for rendering this transparent fire?
it's say:create process fail for mental ray.
thanks for your helps.


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Dec. 31, 2013 2:30 p.m.

hi
when i try to render transparent fire in 2K Resolution (fire close camera) , seems color of fire is blur and color paint by hand (i think need more realistic color for fire)
have we way to control color of fire?
thanks.


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

Dec. 31, 2013 5:16 p.m.

You might find this set of tutorial videos quite useful. It gives a lot of details about the pyro tools in Houdini12. They might be slightly different now in H13 but much will be the same.

Pyro FX 2 Shader Videos
http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=25248 [sidefx.com]

To change the color of fire; you can use the Shop shader for the render, or the Pyro node in the AutoDopNetwork to set the colour in the viewport, then use the Util tab in the Pyro shop shader to ‘Apply All Transfers’

The detail of the fire when close up is related to the voxel size, these are the 3d pixels that are used in the simulation, and the Shop shader settings, that affects the render. Changing these can dramatically add detail.

Good discussion on pyro shader:
http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=28149&highlight=flames+color+colour [sidefx.com]

There is also quite a bit of useful related info if you search this forum and the Odforce ones. try searching “flames colour” and see if it helps.

http://odforce.net [odforce.net]


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Jan. 15, 2014 2:57 a.m.

hi
thanks for your help.
i have new problem for rendering fire in houdini.
when i render fire with mantra view this fire in Mplay and i save sequence in tif but when i open in AE it is just black image and not have any fire on that.
also i open tif file in nuke but fire view with default color for example when i have red fire in Mplay nuke view this fire in yellow color (default color) from houdini.
please help.
thanks.


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

Jan. 15, 2014 3:13 a.m.

Its better if you can upload a rendered frame and the .hip if possible. Thanks!


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Jan. 15, 2014 3:46 a.m.

just render any frame in tif (alpha) and open in after effect.

Attachments:
Fire.hip (1.3 MB)
untitled1.tif (341.8 KB)


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

Jan. 15, 2014 4:30 a.m.

not sure whats up but working here:

Attachments:
firey.png (296.9 KB)


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Jan. 15, 2014 5:25 a.m.

do you render fire in tiff with alpha?because of when i open tiff in AE if i render tiff with alpha AE doesn't show any thing but if i render in jpeg AE show fire very well

can you upload one frame of fire in tiff for me with alpha?
thanks for help


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

Jan. 15, 2014 5:43 a.m.

There is no alpha - its black. Most likely you are premultiplying a black alpha automatically in AfterFX and therefore it will go black i.e. 0.5(fire)x0(alpha) = 0(result)

RMB on the file in Project and change the Interpret Footage/Main to Ignore alpha.

Attachments:
fire.tif (145.7 KB)


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Jan. 15, 2014 5:48 a.m.

how can i render in alpha? like maya?


Nima: Member; 471 posts; Joined: Nov. 2013; Offline

Jan. 15, 2014 11:13 a.m.

when you render fire in maya by tiff sequence it,s automatically in alpha channel and you can use in AE easily.
how can i render in alpha channel?


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

Jan. 15, 2014 1:23 p.m.

alpha normally comes in via smoke, and since this is a ‘smokeless fire’ setup it's missing that - can you upload a maya fire frame with alpha and we'll try to match it.


Skybar: Member; 166 posts; Joined: March 2013; Offline

Jan. 15, 2014 3:49 p.m.

Create a new image plane on your Mantra ROP, write “ fire_mask ” as the VEX Variable and choose Float as the type. On your pyro shader under Utils -> Export you can find other image planes to export as well. Next change the Sample Filter on your image plane to Full Opacity Filtering. Now you can use this as your alpha. It might even work writing “ alpha ” as the Channel Name to get it in the alpha, but I haven't tried that.

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