Hello,
I’m very new to krakatoa and I try to learn the basics via the tutorials in the help file.
In this case the cloud modelling tutorial.
I’ve been achieving the excepted results until I reached the step where you put a channel modifier on the prt_volume, open the magma flow editor and then load the cloud_flow_1 file.
The render isn’t the excepted, it’s over exposed and jagged at the egdes, and I really don’t know why.
Is there any parameter I forgot?
Thank you
Can you upload the MAX scene where you got the problem in a ZIP file?
Most probably the scene scale or the Density settings are different for some reason, but it is difficult to pinpoint without looking at your file.
Thank you for answering
I’ve attached the file
cloudflow_1_error.zip (25.4 KB)
Yep, my first guess was right.
Your System Units settings have 1 Generic Unit = 1 Meter.
The tutorial was made using 1 Generic Unit = 1 Inch (which is the default Max setup in North America).
As result, your scene is significantly smaller in Generic Units, and thus the same number of particles are concentrated in a smaller volume.
Since Krakatoa is a Volumetric Renderer, it reacts strongly to such changes.
The simplest solution is to open the Krakatoa GUI and in the Main Controls UI, change the Exponent of both Lighting and Final Pass Density from -1 to -2.
This will cause the Density used on the particles to be reduced by one order of magnitude from 0.1 and 0.5 to 0.01 and 0.05, respectively.
Also, if you are using the very latest 1.6.1 build or a Beta of Krakatoa 2, there is a [>Use] checkbutton to the left of the Emission Strength spinners which wasn’t available at the time of creation of that tutorial. In these new versions, this option must be checked and the Emission Strength set to one order of magnitude less than the Final Pass Density, or something like 1/-3 (0.001) to avoid an overblown emission channel. Alternatively, you could disable the [>Use Emission] option and go with no self-illumination.
On a related note, the Background Color spinner inside the Global Render Values rollout supports an Alpha channel. In your scene, the Background Alpha is 1.0 which is a bad idea. You can simply set it to 0.0 to get the cloud’s Alpha on a transparent background. Alternatively, you can specify the background color in the Max Render Environment dialog and disable the [>Override Background Color] option in Krakatoa.
I will make some edits to the tutorial to cover these points. Thanks for making us aware of the issues!
Thank you for your advices,
Unfortunately it didn’t work, the same problem persists.
I changed from -1 to -2 in both lighting and final pass density, I also built the scene from scratch, based on generic units = 1 inch, with no success.
I’ve noticed that 3dsmax always crash at the step:
" In the same rollout, enable >Override Background Color and drag&drop the Emission color to the Background color swatch.
Hit RENDER FRAME to see the result - a second lighting pass with the self-illumination (Emission) color will be calculated and the background will be set to the same blueish color:"
When I hit render this first time, max crash every time. I save in recover mode, then reload the recovered scene, hit render, and it works.
Hope you can find what’s going on.
Did you tweak the Emission as instructed?
Thank you
It did improve the situation.
But this time the cloud isn’t blueish like in the tutorial, the background is blue, but the cloud remains grey as if override emissions wasn’t used.
I’ll keep trying to tweak
True, there were some significant changes in the way v1.6.0 and higher deal with the Emission channel.
This was necessary in order to provide better control for FumeFX Fire rendering and mixing with volumetric Smoke.
A possible way to achieve the same result as in 1.5.0 is this:
*Open the Global Values rollout
*Press the button “Create New Global Override Set” - this will create a global KCM
*In the KCM, set the Output to Emission
*Set the Input to Value and copy the Emission color into it.
*With the input node selected, hit * to add a Multiply node.
*With the Multiply selected, hit SHIFT+D to create a Density input.
As result, the Emission is now multiplied by the Density.
*Disable the >Override Emission option so the KCM would be used instead.
*Disable the >Use option for the Emission Strength to use the Final Density value.
This should produce the blueish tint in the cloud. It does for me here using v1.6.1.
I will further modify the tutorial to explain this.
Thank you again
I have to say that I can’t reproduce the same results as you did, and I did follow your steps one by one very carefully, and even repeated the whole process several times.
I’m searching for a mistake I did in the process but, even when doing and redoing it, I can’t manage to succeed, the cloud remains gray…
Is there any param in my version ( I use 1.6.1.44739) set on default that could cause this?
Nope.
I am uploading the modified version of the scene you sent me so you can keep on going…
See if it renders ok on your system, it looks as expected here.
It has the global override KCM with the Emission multiplied by Density, Emission Color Override off, Use Emission Strength off.
Here is what I am getting:
cloudflow_1_fixed.zip (24.8 KB)
Thank you for your upload.
The cloud is rendered blue as expected.
I’ll search in the params and compare my scene to fixed one…
That should be easy : just open Presets and History rollout
and select two records, one old and one new, and you will see all differences.
I wanted to thank you for your advices bobo, it’s been a good source of information, I didn’t have the time to check that yet due to other work, but I’ll do this comparative soon, which will certainly improve my skills if God wills…