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Houdini Indie and Apprentice » Height Field Tools

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tamte
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Make sure you are in SOP context

If you are at Object level place Geometry node and dive inside then you should see them in TAB menu
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Solaris » how do multishot setup

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tamte
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if you make sure all your camera nodes output to the same prim path then switching should not kick you out of the viewport camera as it will able to find camera always under the same path
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Houdini Indie and Apprentice » Scattering/ "for each point"/ timeshift

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tamte
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didi5000
So I'm having this case where I have 100 variations of a plant in a single file cache, each on a different frame.

try loading all your frames at once using File Merge SOP (as Packed Disk) so that you have 100 packed primitives as a static geo
then you can just copy using Piece attribute on Copy SOP to pick one variant per point, no foreach, no timeshifts
Edited by tamte - yesterday 10:52:52
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Houdini Indie and Apprentice » Fancy new Tangentfield

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tamte
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simple example, feel free to use field1 instead of field0 to get flow in perpendicular direction
Edited by tamte - Aug. 9, 2022 17:44:32
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Technical Discussion » Batch renaming KineFX rig ?

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tamte
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use Attribute String Edit SOP
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Houdini Indie and Apprentice » Fancy new Tangentfield

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tamte
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toonafish
When I then try to rename the "field" attribute (coming from the tangentfield I suppose) with the "attribute rename" all I get is a "field not found" error.
as mentioned it's called field0 not just field
you can also use field1, field2, field3, those are directions that tangentfield produces by default, MMB on the Tangent Field node to see the names
Edited by tamte - Aug. 9, 2022 14:52:20
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Houdini Indie and Apprentice » Fancy new Tangentfield

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tamte
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just rename field0 attribute (or any of them) to: up
add N
then scatter some points and copy
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Solaris » Dark refractions with material X

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tamte
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it's hard to debug based on screenshots, maybe post your file or simplified example
did you try raise SSS limit above 0 since you are using SSS?

I tried on a simple scene with SSS, it seems to behave pretty realistic without any special treatment
Edited by tamte - Aug. 9, 2022 04:05:02
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Solaris » Dark refractions with material X

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tamte
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mzigaib
So if it doesn't, cast shadows on itself it should not get those darker internal refractions with caustics and dielectrics correct?
it is still casting shadows on the apple, and you can see those shadows through refractions
those shadows can be brightened by caustics, but obviously you don't want them to be completely gone in case like droplets, otherwise it wouldn't be realistic
of course it also depends on your lighting
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Solaris » Dark refractions with material X

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tamte
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mzigaib
I am referring to objects not casting shadows on itself but the rest
that's what I initially thought you meant by self shadowing, but since it's not possible for dielectric object to cast shadows on itself (since it doesn't have any diffuse, sss or volume component) so I assumed you potentially mean just shadow casting
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Houdini Lounge » Physical Sun and sky system for Karma XPU - feature request

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tamte
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I personally don't have various HDR sequences of day-night cycle or cloud timelapses lying around
and also I'm jealous of how easy the Unreal kids have it these days with lighting environments

so for me lazy options please!
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Solaris » Dark refractions with material X

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tamte
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BrianHanke
mzigaib
BrianHanke
I've experienced similar issues and despite tons of experimenting I can't make it look good. It's way too hard to get simple caustics working in Karma when in other renderers it's usually just a matter of ticking a checkbox. I think I'll email SideFX to see if their Karma gurus can recommend a solution.

Thanks for the feedback! I am not tech savy enough to figure what is going on under the hood, for me it seemed like a self shadow issue where in Mantra a simple faux caustics would fix it. Having a "easy" option to exclude self shadow would also be useful.

Yep exactly! Faux caustics should help, but it's hard to control as I posted about a few days ago. Excluding shadows would also be great. Arnold in Maya has a "receive shadows" checkbox which seems like a pretty basic feature that isn't present in Karma.

- if you don't want your droplets to cast shadows, use Render Geometry Settings, Enable Render Visibility and set it to: -shadow

- also some shadowing is natural for dielectric surfaces, simply the reflected portion is light that will not reach the surface therefore will cause shadow, so turning shadows completely off will most likely be unnatural, but its an option

- faux casutics are automatic when real Caustics are off even though in that case there is no additional control on top of IOR
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Solaris » Dark refractions with material X

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tamte
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jsmack
Does the droplet geo go inside the apple skin geo? If so, then it could be shadowing the SSS scattering on the inside, as I don't think SSS paths take caustics into account.
they should with SSS limit > 0
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Technical Discussion » how to understand Ambient Temp(K) and Reference Temp(K) ?

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tamte
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temperature in pyro is in ambiguous values where 0 is always ambient temperature and 1 can mean be whatever

however to help getting real world based buoyancy, there are those Kelvin sliders that are then used to compute buoyancy by assuming 0 is Ambinent Temp and 1 is Reference Temp

similarly those values can be used for shading if you use blackbody (Temperature at 0 and Temperature at 1)
Edited by tamte - Aug. 7, 2022 15:19:02
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Houdini Indie and Apprentice » Cleaning attributes on FBX import.

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tamte
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select your FBX object subnet(s) that contains the imported fbx objects and paste this into python shell or create shelf button out of this

nodes = hou.selectedNodes()
for fbx_subnet in nodes:    
    if fbx_subnet.type().nameWithCategory() != "Object/subnet":
        print("Skipping {}, not a valid Object subnet".format(fbx_subnet.path()))
        continue
    
    for node in fbx_subnet.children():
        if node.type().name() == "geo":
            render_node = node.renderNode()
            mat_attrib = render_node.geometry().findPrimAttrib("shop_materialpath")
            if mat_attrib:
                ad = render_node.createOutputNode("attribdelete")
                ad.parm("primdel").set("shop_materialpath")
                ad.moveToGoodPosition()
                if node.renderNode() == node.displayNode():
                    ad.setDisplayFlag(1)
                ad.setRenderFlag(1)
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Technical Discussion » ROP in compile

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tamte
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You can also use TOPs to process multiple iterations in parallel instead of compiled foreach
Edited by tamte - Aug. 5, 2022 13:43:29
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Technical Discussion » How to Use One Point attributes on Other Points in a VOP?

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tamte
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plug Constant VOP with the value 0 into ptnum input of your import_cam_point node

OR

you can completely avoid the hassle of creating null or objectmerging a point and just transform all your points P to camera space and get the length of it (assuming the camera doesn't have any scaling, which is the default behavior of houdini cameras)

in VOPs it would be:
P -> Transform VOP -> Length VOP -> Bind Export (distance)

Transform VOP would be set to:
from Space: space:current
To Space: ../rel/path/to/the/camera (ideally promote this input and change String Qualifier to List of Objects/Camera Only and disable menu)


in Wrangle:
string cam = chs("cam");
f@distance = length(ptransform("", cam, v@P));
Edited by tamte - Aug. 4, 2022 22:38:08
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Technical Discussion » Particle Sprite with Karma？

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tamte
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jsmack
so geometry that looks different from different angles won't work.
what about rendering curves as ribbons? isn't that the same principle?
Karma supports those, so why wouldn't sprites

EDIT: or even rendering particles as discs should be rendered based on ray direction, are you saying it's not the case with Karma?

EDIT2: just checked, it renders discs properly based on ray direction, so no excuse for not having proper sprite type
Edited by tamte - Aug. 3, 2022 22:25:39
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Technical Discussion » Particle Sprite with Karma？

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tamte
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looks like a big oversight, particles should definitely have a sprite rendering mode

you can't fake it with lookat constraint, not only it is tedious workaround
it also doesnt behave like sprites

the main advantage of sprites (at least to my understanding) is that they face all the rays that evaluate them (like for shadow cating etc...), unlike oriented rectangles
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Technical Discussion » Karma Hair Melanin Colorspace

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tamte
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ideally there would be a separate node that generate melanin color based on related attributes that can be plugged to anything, including hair shader, to avoid monolythic nodes with too many controls and also to allow inserting anything like color transform inbetween
since melanin based color can be useful for much more than just hair
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