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Everything posted by davpe

  1. UV Flatten BEFORE OR AFTER subdivide?

    i would generally use it before subdiv, but after bevel. but it may depend on your particular situation you're dealing with
  2. Orient object along it's velocity

    when animation stops, then velocity = 0, so is the orientation. you'd have to make up a logic for that situation, based on what do you want to happen if the object is not moving (or limit the velocity to some minimal value that appears to be zero but it's not - so you'll still get the orientation vector) velocity distance is: @vdist = length(@v);
  3. Orient object along it's velocity

    well it doesn't make any difference whether the object is animated or not. i just added a transform SOP animation and Trail SOP to my setup. otherwise it's the same thing. look at the hip file attached. orient_along_vector.hiplc
  4. Orient object along it's velocity

    well, yeah, so what's the issue? copy to points works like a charm... see the animated gif bellow.
  5. Orient object along it's velocity

    i guess technically the easiest solution would be to make your object a packed prim and use that to drive your unpacked geometry with copy_to_points_SOP, while velocity used as N. a bit odd in terms of workflow but hey, it's easy (easier than it sounds ) and it works. see the attachment for hip file. you can also build a quaternion orient attribute to make it more flexible and to allow continuous rotations without axis flipping. orient_along_vector.hiplc
  6. Is it a Cache Problem?

    if you're not caching your simulation, then you should. you always want to do that to avoid possible issues in rendering stage (with any renderer)
  7. i don't know what you expect to get but your example works. you've got two uv attributes and redshift renders two ramps oriented by those uv attributes. isn't that what you want?
  8. UV layout pack by Prim

    why don't you use more UVLayout nodes? just split your geometry into desired geometry pieces, UVLayout each of them separately to whatever number of udims you want, and then just offset individual UV sets to where you want them.
  9. Render layer setup

    you can do Extra Image Planes as Mangi suggests, which are more like AOVs within one render pass (i.e. specular, diffuse, depth, etc) or you can do separate render passes that each have it's own render settings and everything. that's done by simply creating more Mantra ROP nodes. within Mantra ROP (in Objects tab) you can specify which objects are rendered or excluded from rendering, which are contributing lights for the current ROP, objects that are only rendered as secondary rays or masked out in alpha. additionally you can force any object to have certain visibility settings regardless what Mantra ROP says (this can be set on the object itself in Render tab and Render>Shading tab). Also you can use Stylesheets to conveniently do object level or scene level material overrides (while each Mantra ROP can render different Stylesheets). in addition to this there is also a decent array of nodes that can manipulate object visibility on shader level (like shadow casting, treating object rays separately from light rays and stuff like that). these features combined give you heaps of flexibility for any kind of render passes/AOVs you can think of.
  10. you can freeze an animated object on the first frame with Timeshift SOP, do the transfer, and then reapply the animation with Attribute Copy SOP. this is topology dependent so you can't do any topology alterations in this process.
  11. houdini 16 group node

    i'm not sure what the exact difficulty are you experiencing. point group by bounding box works right away for me - only you have to set the group type to points instead of default primitives. not sure if it was perhaps defaulted to points in the past. After that you can convert the group from points to primitives by Group Promote SOP. Generally, groups functionality is the same (actually it has a few more features now), so in this area you shouldn't really experience any major difficulties following older tutorials - only you have to remember Group SOP has been split into more simpler groups related nodes.
  12. ...or you could switch the refresh mode to "Manual" to avoid any nodes cooking automatically. You can find it right next to the brain icon in the bottom right corner. It will only cook the thing if you hit the refresh button. super useful for heavy scenes. another helpful thing you can do is to disable displaying of "Current geometry" in Viewport Display Options. Current geometry is a node that is selected but does not necessarily have a display flag on it. So in some node trees, whenever you select something, Houdini starts recomputing that part of a network as it wants to display it together with a display flag node. Generally it's useful, but in heavy scenes this can become a real drag and turning it off can improve interactivity a lot if you're working with big networks. (It's in Viewport Display Options>Guides, in top right area. You can access the dialogue by pressing D while hovering mouse over the viewport) you can't avoid "freezing" Houdini while it's cooking nodes thou - you would end up stuck in an endless re-cooking loop of your last actions, without ever finishing it, until you allow enough time to actually compute the result - which is exactly the "freeze time" you're experiencing. cheers
  13. well as I said, it's hard to tell without inspecting the hip file mine is rendering fine... check the file attached, maybe you're doing something wrong in your setup. displ.hiplc
  14. white dots look like obvious specular undersampling but hard to say exactly without inspecting the file. this displacement issue is typical if bound is not large enough. post a hip file if you want more people to respond. this is very hard by just looking at the image. cheers, D.
  15. How much instances can I render?

    well as I said... packing trees into 1 primitive helped a lot. and then i don't think you can assign a material to packed prims. it's best if it already is a part of packed geo. there are ways how to post-apply materials to packed geo, but doing what you did does not work. i don't know thou why it had such a huge impact on render startup time. i would simple expect it will not work and you'll get a blank material render or something... in any way, don't do this if you absolutely need to apply material to geometry that already has been packed you can use material stylesheets (this can also result in poor performance with big shots, so be careful) or there is Edit Packed SOP (haven't used this one much so not sure about possible performance penalties). anyways, the best thing is just to have materials packed together with geo and then maybe do in-shader variations per instance if this is what you're after. cheers.
  16. How do you learn mantra?

    ok so let's see. number of poly is not an issue. issue was an unreasonably high render settings, even thou you felt it's low. in your picture, there isn't very high contribution from indirect reflection rays, yet you've had reflection ray depth set to 4 and on top of it, reflection quality set to 2. those were your main slow down factors. I was able to render exactly the same looking picture in 8 mins with ray limits to 1 and quality to 1. generally I mostly start with ray limits at 0 and then I don't go beyond 1 even for the final renders unless there is a significant visual difference and I can't achieve it other ways. your scene is just too simple to benefit from multiple reflection bounces but still those had to be computed by Mantra, and have gotten exponentially more expensive to render. it would make more sense, by the way, to increase number of diffuse bounces to 2 as you've got a huge white background there that would bounce a lot of light around (if you wanna go fancy - see the last pic, 1 refl bounce, 2 diffuse bounces, render ~11 mins). reason for your background having artifacts was it being nurbs surface. I have never used nurbs surfaces for rendering, so not sure why exactly it was rendering wrong but when I converted to polygons shading turned out fine. and just for info, this was rendered on my laptop with 4-core i7-7700HQ. so yours should be even a bit faster. cheers
  17. How much instances can I render?

    the hipfile GEO_CITY_22_loop_fast.hipnc
  18. How much instances can I render?

    oh sorry, i forgot to attach that hipfile. will do once i get back to my desk. i just rewired your setup a bit and it really isn't any slower.
  19. How much instances can I render?

    i disagree with you. render the attached scene. copy sop in loop, frame finished in 6 mins on my laptop. yes diffuse bounce made a big difference. it depends what you need thou and you don't always need it for aerial shots like this. many times I successfully used a trick with another lowres enviro light with low importance sampling - so it's super blurry but it still retains shadows of bigger shapes - this makes a great job bringing dark areas up. if you're far enough nobody can tell whether it's a fake, and it renders super fast, plus you have extra control over your contrast levels. of course it depends on many factors if you can use that trick or not - you just may need that bounce to make it look right sometimes, but for wide shots with many tiny details this can be very useful. just saying
  20. How much instances can I render?

    here. your scene rendered in 6 minutes on my laptop, with close to zero startup time, and consumed 700 mb of ram. what I did - first of all, the reason for your high startup times and crazy memory demands were actually nested packed primitives. nesting itself would't be an issue if you weren't nested thousands of packed prims... that actually makes packed geometry more expensive than rendering just plain meshes. just have one packed prim per tree - or maybe two if you want to separate leaves and wood. so if you unpack completely your tree and pack it again as one primitive, you should see much better performance. another thing is your render settings were completely overkill in some points - like ray limits. with trees or very detailed geometry i find having pixel samples quite high as needed so 8x8 is fine, but setting ray limits to zero made almost no visual difference (in this particular render) and renders faster. you don't necessarily want to have zeroes in ray limits at the end of the day, but point is to cut it as low as you can (and what you've had set there was definitely overkill for this king of rendering). also, rendering a depth of field is something I have never seen done on any project in any vfx house. very expensive to render, and if you don't get it right you have to render the whole thing again. maybe in some very special case renders it makes sense, but generally you do that in comp. regarding instancing in general, i don't think instance object is any faster than copy SOP in it's essence, as a few people mentioned here. it's just that copy SOP gives you more freedom to do stuff and that naturally leads to longer cook times. instance object simply forces you to obey the most efficient workflow. copy SOP in loop is actually the most efficient workflow if you need more than just a bunch of static objects distributed over the points. but if you do a very simple instancing like you do in your scene it actually doesn't make sense to use loops as you're not using any of it's benefits. (but still I haven't found it slow to cook, it was like maybe a half of a second??)
  21. How do you learn mantra?

    it's true that for mantra, there aren't really any recent detailed tutorials to watch (which is a shame). essentially thou, Mantra is the same thing as any other pathtracer. so if you already know how to use Arnold or Renderman you can translate a lof of this knowledge to Mantra. i have switched to mantra from using mental ray and arnold (like 5 yrs ago or so) and it didn't take me long to understand all the essentials. sure you've got some different names and options to turn on or off, sampling is split into a bit different controls etc. but I mean still you have your pixels and ray samples, ray limits, bucket sizes and so forth so it shouldn't be that big of a deal. reading houdini documentation helps a heaps. mastering Mantra is something that takes a long time thou, for the following reasons: mantra has TONS of controls you can use to optimize (or de-optimize) the rendering process. That's sort of good and bad thing at the same time, depends on what you want and how good understanding of these settings you have. I like having a lot of control so I love Mantra for giving me million sliders and toggles that many users never touch. You can do stuff with it that can save your ass sometimes - because you can for instance render out some odd render pass that helps compositing tremendously and saves you from running an expensive render. Or sometimes you realize that if you use this in combination with that, you can very easily render an effect that would be otherwise painful or time consuming to do. Unfortunately, "uneducated tinkering" can equally well turn your "grey sphere on a checkerboard" into rendering nightmare that takes 90 hours to complete - your call Some people are driven crazy with that bcs they just want to set the slider to "good quality", hit the render button and get that picture done (can't blame them). One objectively BAD thing in Mantra, especially for new users, is that among it's numerous parameters (half of which is actually "hidden", and you have to go to Edit rendering parameters interface to access it) there are a few inconspicuous ones that can make a big difference in how long and in what quality your picture actually renders (in some cases), and there is no way to know unless you're told, or you spend time figuring out why this particular scene eats up 100GB of ram if there is apparently no reason for that. Then you discover this hidden parameter having completely inappropriate default value (which turns out to be an issue if you render more than certain amount of texture data in your scene for example). i personally think stuff like this is one of the main reasons that makes many users turn to some easier-to-grasp solutions like Arnold, that is quite limited in what you can do with it, on the other hand thou, it's very easy to use, and you don't have to be an expert user to get quite consistent and predictable results. So my advice on learning mantra is, learn how raytracers are working in general, then read the docs and then do a lot of experiments with things you're not sure about. Having said that, in this article you can read about some of those nasty hidden parameters: https://vfxbrain.wordpress.com/2016/03/16/mantra-tips/ And maybe some more tips here: https://vfxbrain.wordpress.com/category/rendering/ cheers.
  22. Cloud timelapse approach?

    I've done similar stuff in past with simply animating a noise offset.
  23. Houdini + ZBrush

    that's pretty cool!
  24. sometimes Clean SOP with Orient Polygons option ON works. that should fix individual crippled faces. not the whole islands thou... maybe combination of methods is the best way to go... really depends on the particular model.
  25. Copied relative reference issue

    the best way would be only to use one copy_to_points SOP and have an attribute on the template points that specifies what object is going to be copied onto them. watch this video. stuff you want starts at about 06:20