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catchyid last won the day on November 20 2016

catchyid had the most liked content!

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About catchyid

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    Khaled Abdelhay
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    Montreal, QC

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  1. Pyro workflow question

    Thanks Atom...have not used gastarget before, but the name itself is promising I use low res to iteratre quickly, so I wonder you start with high res as you mentioned, don't you find too slow? thanks for that expression, it will make things more under control....but i am thinking, having a simulation farm will actually solve the problem?! have not tested it, but a company like ILM must have a huge simulation farm that makes very easy to sim *any* thing quickly!?
  2. Hi, This is a general question just to know how other artists tackle this issue. When simulating a pyro shot, i.e. cigarettes buffs, I start with low resolution to get the motion right. Using low resolution guarantees that I can iterate quickly, hence get the initial look/feel I like quickly. However after that, I want to produce more detailed simulation, so I run higher resolution simulation (i.e. smaller voxel size), but the problem now is I usually get different shapes than the original one?! Since it's a higher resolution, iterations are expensive and takes longer and I find it hard to reach my goal in a timely manner! Now, my question: how other artists deal with this problem? Is my workflow right or I need do something different. Thanks,
  3. Hey, thanks for your answer I think my question was not clear I wanted to know how to read/write vel.* in volume vop? I found out one can do that using "parameter" operator in SOP context, OR "bind" operator in DOP context. I am not sure why there are two ways to read it (why not just use bind in all contexts). I will create a sample file to show you what I mean (but I am about to take off now, so most probably will do that on Monday)....Thanks Colton for your quick reply...
  4. Hi, If I have a density volume (i.e. a scalar volume), then I can use volume vop and connect something to output "density" to write to it. However, if I have vel.x, vel.y, vel.z, (i.e. a field volume) then how can I then write to them inside a volume vop? I found out that "parameter" operator will do that, however, I am confused, vel.* is a voxel data and not the "typical" definition of a parameter (which is a value per an operator)? I know it's not that important to know why (as long as it works), however I would appreciate it if someone sheds a light on this logic or maybe different way to write into field volumes (either VDB or native Houdini volumes) Thanks
  5. Alright, really appreciate your help, thanks
  6. Thanks You are correct. I think it's a bug, don't need to worry about a fix. Another thing, have you noticed that that bottom sphere after isooffset seems has some noise? i.e. it's not a clear fog like the top one? Once more thanks for your help
  7. Hi, I want to combine different volumes into one single volume. If I use native houdini volumes, I get bad results, plz see attached (used both volumemix and volumemerge). However, If I use VDBs + vdb combine, I get good results. Is this normal OR I am doing something wrong? volumes_union.hip
  8. Hi, Let's say I want to emit dust/snow from car wheels and make it look organic (i.e. sputter emission, different shapes, etc.). As far as I know, there are two ways to do that: A- add noise vel (e.g. curl) to the density source, or B- add a pre-roll noise vel such that once density is emitted it gets advected by the nosie My biggest problems with the above two methods is their complete randomness, meaning: in one sim the emission pattern looks nice, but the rest of sim looks bad, or vise versa. In my tests, B produces better results, however density keeps advected by the noise no matter how far it's from the source which looks "strange" (my goal is: organic emission, then density diffuses gracefully eventually, i.e. the more time passes the less turbulent it becomes). Using noises as above is very time consuming and makes feel like I am rolling a dice, each time I change noise parameter and "hope" it will give good result. I am wondering what other artists do to control the sim and produce results quickly for an effect such as effect. A visual reference of what I want to achieve is this:
  9. Yes, start with VOPs...almost the same but it's visual...
  10. ocean fluid extend issue

    I am still new to FLIP, but I always find these pumps/creases! the only workaround I do is to expand the ocean beyond what camera sees! Not a solution, but I would be very interested to know if there is a way to get rid of it...
  11. Hi, according to documentation "particle radius scale" is defined with respect to "particle separation" as Now, I am confused: if particle separation is 0.1 then the max particle radius should be 0.1/2 otherwise particles would be colliding with each other? I feel these two parameters should be tied automatically and not defined independently (e.g. if particle separation is 0.1 then particle radius must be less than 0.1/2). Also, if I say particle separation is 0.1 and particle radius is 0.5 then would that mean I would have partially empty voxels? I am confused as you can tell! Any help is appreciated
  12. hello, Sidefx site has lots of tutorial (free and paid), just visit https://sidefx.com/tutorials/ and "vex" as keyword and you will find lots of hits... one hit that I think for beginner is (just googled vex webinar). Don't worry too much about old houdini versions, I "think" vex code is not changing much (maybe adding more functions, but I think it's mostly backward compatible)
  13. switch in vex?

    Brilliant! Thanks for your answer, very clean and obvious
  14. switch in vex?

    Hi, I need to switch between multiple inputs in SOP, I can use switch SOP node, but since I have many switch condition, I think it would way easier in vex (as opposed to having multiple switch nodes connected together). I could not find a vex function that switches between input, or am I missing something?