Motion Blur on Particles
polycounter lvl 6
Hello,
I'm fairly new to UDK and even though I've been practising particles and simulations in Maya and Realflow I thought I should try the particle system in UDK. I'm working on a scene in which there is snow, fog and mist and the problem that I'm having is with the Motion Blur for the snow.
I did some research and I found out that there are two different techniques to do MB in UDK, Soft Edge Motion Blur and Camera Motion Blur. Since I only want the snow to be affected by MB I assumed that I had to use Soft Edge Motion Blur and not Camera Motion Blur because I don't want the MB to be generated from the camera's movement, but instead from the particles' velocity.
I followed a guide from UDK in the help file, but I couldn't get it to work. The end result did not affect the particles in any way and just blurred the viewport, changing values and tweeking the settings didn't make much of a difference. The way I overcame the problem is I edited the scale of the particles to make them look more like lines of snow and less like dots of snow (tried to "fake" the MB). I'm still not entirely happy with the result that is why I'm asking here in the forum for any help to get the MB on the particles to work.
I've attached a screenshot of what I'm working on, to give you a clearer idea of my problem. Any help would be much appreciated, thank you.
Link to screenshot: http://i807.photobucket.com/albums/yy360/yanni_1988/Polycount_MB.jpg
I'm fairly new to UDK and even though I've been practising particles and simulations in Maya and Realflow I thought I should try the particle system in UDK. I'm working on a scene in which there is snow, fog and mist and the problem that I'm having is with the Motion Blur for the snow.
I did some research and I found out that there are two different techniques to do MB in UDK, Soft Edge Motion Blur and Camera Motion Blur. Since I only want the snow to be affected by MB I assumed that I had to use Soft Edge Motion Blur and not Camera Motion Blur because I don't want the MB to be generated from the camera's movement, but instead from the particles' velocity.
I followed a guide from UDK in the help file, but I couldn't get it to work. The end result did not affect the particles in any way and just blurred the viewport, changing values and tweeking the settings didn't make much of a difference. The way I overcame the problem is I edited the scale of the particles to make them look more like lines of snow and less like dots of snow (tried to "fake" the MB). I'm still not entirely happy with the result that is why I'm asking here in the forum for any help to get the MB on the particles to work.
I've attached a screenshot of what I'm working on, to give you a clearer idea of my problem. Any help would be much appreciated, thank you.
Link to screenshot: http://i807.photobucket.com/albums/yy360/yanni_1988/Polycount_MB.jpg
Replies
I think that the main problem here is where you are putting your focus. As an outside viewer (or player) i would try to focus on the buildings and not the particles themselves, much like you react in the actual situation of a blizzard. You as the artist however stare yourself blind into this detail thats only there for ambience.
That didnt really solve your issue however but i hope it was helpfull anyhow.
Any feedback is good and appreciated. You are right that by cranking out the fog and filling the whole place with snow I shifted the focus, in this project I'm in charge of the particle simulations and the effects, I might have overdone it a bit but this screenshot is from the Alpha version, I think once those buildings are textured (I didn't model anything in that scene) and we put some nice night lighting the focus will go back to the buildings and to the scene. For now the buildings are untextured and they receive the colour of the fog, that's why they blend in with the scene so much. I'll keep in mind your comment though and see what it looks like once they have finished texturing the environments.
Regarding the MB, I think you're right, the snowflakes wouldn't have enough velocity to actually generate MB. I was just worried that I was doing something wrong or I was missing something. The way I did it, isn't that bad (me thinks), seems to work and gives a variation to the snowflakes' shape.
Anyway, thank you for your feedback, much appreciated.
Also, by Motion Blur, are you talking about image interpolation, or the streaky/smudging effect of fast moving objects? Image interpolation just makes travelling subjects move smoother, as if they are still travelling between frames.
With your snow, perhaps just slowing the particles down and creating a higher density would get your blizzard effect across better. Or maybe having them be effected by wind more - instead of travelling almost straight down, have them go sideways a lot more at speed.
Sorry I didn't understand correctly the difference between those two types of Motion Blur. By MB I meant the softness/blurriness of moving objects, like a ball bouncing around.
To be entirely honest with you my snow doesn't have a wind force affecting it, I was looking for forces in the Cascade like Turbulence, Gravity, Drag force etc but didn't find any, so I assumed they don't use forces in the Cascade. If you could please tell me where can I find the wind force that would be great. The way I "faked" the wind was by setting up their velocity and having an Acceleration node. I also added an Orbit node to make them move less downwards.
I don't know much about limitations in games engines so forgive me if I'm wrong, the way I did the snow is I created an emitter with an initial location of X/Y/Z scale, then I duplicated that emitter X times to fill out the town that you see in the picture. If I increase the number of particles that each emitter generates, then the particles start acting weird, you'd see big chunks of snow then no particles, then big chunks again, then some particles etc. The birth isn't fluid, if you know what I mean (I'm not sure I'm explaining myself very well - English isn't my first language). The reason for that is, I think, that UDK as a games engine can not allow loads of particles to be generated at the same time that is why it acts like that. I tried to bypass that problem by decreasing the life of the particles and increasing their speed, I also added a Kill node to kill the particles once they reach a certain distance. That way more particles die, more particles are generated. I'm not sure if this is the best way to make the snow more dense.
I've just finished downloading a tutorial that I found here called "Cascade: The Complete Beginner's Guide", maybe I'll find information about forces in UDK.
Thank you very much for your help and feedback. It only works to make my work better :P
Awesome
Anyhow im looking foreward to seeing your scene progrss it looks really promising and i hope you open up a thread here so we can follow your progress.
I like what i have seen sofar!
It might also be a good idea to add a Kill Height module so that the particles die below a set height
I haven't looked into it myself, but I'm pretty certain that you can place a Wind Actor in your scene and have the particles interact with it by applying some settings in Cascade, too.
I was watching the sparks tutorial yesterday (the free one), just to see how well he explains stuff and I can honestly say I was really satisfied with the tutorial. Nicely explained, easy (for international people) to understand and with a hint of humour (!). I'll go through the Cascade Beginner's Guide when I get a chance.
I found the Max Draw Count in the Rendering Tab, helped a lot. Would you say it's better to make a massive emitter and cover the whole village and generate thousands of particles from one emitter or have many small emitters duplicated? What's some sufficient for a games engine? And one more thing please, is there a way to see the 3D Draw Model of the Initial Location module in the scene?
Before, when I said Kill node, I meant the Kill Height module, sorry I keep calling them nodes. I'll play around with the Wind actor and see what results I'll get. Thank you for your help.
Cascade doesn't really have forces much like other particle systems. Things like wind and gravity are controlled by velocity and acceleration, among others.
For something like snow, I'd attach something much smaller to your camera and make sure local space is off. Covering a whole scene with one emitter wouldn't fly in most production environments. You could also make one small particle system and place it multiple times throughout the scene. Then use LODs to activate it at a certain distance.
Viscreal is right, FAKE IT
I hope you are enjoying the Begginer's Guide!
Also, another thing you could do is make a plane, with a DepthAlpha with a phong like texture and alpha for transparent effect, rush towards the player from a certain/wind angle.
This way, you're essentially faking the rush of fog and snow draft towards the player at the cost of 1 plane at set intervals. Just make sure it plays nice with the direction of the Snow.
Not sure if I'm making much sense, but hopefully, you get the gist of it.
I thought you where american, how can you spell Beginners wrong
(i wouldnt commented on it if you havent also spelled my name wrong!)
Anyhow i highly recomend ImbueFx tutorial, cheap and as high quality as any gnomon or eat3d video if not moore. loved the last optimization part, learned alot from that one!
Sorry I have been replying to so many posts lately, I just fly through them and never look back. But I'm glad you dig the set and the optimization chapter. I actually thought most people skip it.
finally I had the chance to work on the snow again, due to other university projects I had to focus on other things for a few weeks.
I made a new texture, and created a new material. I tried to improve the simulation by adding Acceleration and Kill Height and generally make it more believable.
One problem though, it seems like the DebthBiasedAlpha of the material is not working at all. No matter what value I put in DBA there is no difference. The snowflakes don't fade out when they touch other geometry or when they are close to the camera (this is my main problem - I need them to fade out when they are close to the camera) and the same thing happens when I preview it in the material editor.
Here's a screenshot of a snowflake close to the camera: http://i807.photobucket.com/albums/yy360/yanni_1988/Capture.jpg
The material in the material editor: http://i807.photobucket.com/albums/yy360/yanni_1988/Snowflake_MAT_Forum.jpg
What you see in the preview window of the material editor is the clipping of the texture when the camera is close to the material. I tried re-creating the material, tried different values (from 1 to 5k) in DBA, nothing, no difference. I don't know what's wrong, thing is I use (more or less) the same set-up for the mist material and DBA works fine there.
Also here's a video of my simulation (up until now), the environment you see is not the final, it's an early version my team gave me to work with for the simulations. Any feedback, suggestions regarding the material or the simulation is needed and appreciated. Thank you in advance.
https://vimeo.com/38671580
Also as a side note..did you plug in your normal map to your diffuse channel? Beacuse the gound looks like a washed out normal map
The only thing that bothers me with the snow is the DBA, once that is fixed I think I will be able to call the simulation finished.
Here's a screenshot of the material tree. Notice how I'm boosting the texture by 25 times, do you think that could be messing up the DBA? I guess I could boost the texture in Photoshop and then reimport it with a constant of 1.
Thanks
I've never had pixel depth going in to a DBA, so it might be worth a shot eliminating that.
How should I connect the Pixel Depth to the material?
Bear in mind, for logical values in pixel depth, if you multiply it, its 1/Unreal Units.
So 1/256 becomes 0.00390625, which should make your particles disappear over 256 units.