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Solaris and Karma » overview of how to combine aov's for beauty reconstruction?

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Dougie0047
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 April 25, 2025 13:37:19
@bogdana Thanks for your answer. Yes, so putting together all the additive passes is fine and dandy. And staying away from shadowed/unshadowed is also fine. However, I would like to understand how they are designed to work still. But I cannot find any resources on it at the moment. The albedo I would very much like to use however. And I've tried dividing the albedo from the combined diffuse for example. But, mostly, you do not get what you expect, which is just the raw light. There always seem to be some residue of color in the result, and that should not really be the case. So, how are we meant to use the albedo pass? And, why is there only one albedo pass easily available? For what is it meant for? Just the diffuse or more? Other rendering engines offer albedo for more than just the diffuse. So, this still makes me curious.
Does anyone has good info on this?

Cheers,
Dag
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Solaris and Karma » overview of how to combine aov's for beauty reconstruction?

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Dougie0047
88 posts
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 April 23, 2025 12:44:33
Hello there, I'm looking for a detailed explanation of how to combine the regular as well as somewhat unusual aov's to reconstruct the beauty, but I'm currently not really finding anything of use in the documents. Perhaps I have looked in the wrong place? Or, does such an overview not exist? I am thinking along the lines of something like this page here: https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_maya_aovs_am_AOVs_for_Image_Compositing_html [help.autodesk.com]
So, basically a way to look at how the aov's go together mathematically.

I know that most aov's are additive, but Karma can also very easily output aov's named something like "shadow", "unshadowed", albedo etc. which, presumably, are not just straight additive aovs. And, of course, most of the time there are certain "sets" of aov's that are meant to be added together vs. other sets.

Can anyone point me to a good source of information for this?

Thanks,
Dag
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Technical Discussion » patterns per side of building?

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Dougie0047
88 posts
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 March 8, 2025 06:04:52
Hello,
I'm testing out the labs building from patterns to set up some simple house models, and I'm wondering if there is a way to create a pattern or method that allows me to treat each side individually? I cannot seem to come up with something good here. It seems that the patterns we can create apply to every single section of the building. So, am I missing something here or is this a limitation of the node? I also tried to input a grid instead of a box, and that does not work. So, is the only real option here to create 4 entirely separate versions of the model, then delete the portions according to which wall pattern I need, to then re-combine them into a new model? This sees very convoluted, so if anyone has any tips for a better way of doing this I am all ears!

Cheers,
Dag
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Technical Discussion » most efficient with height fields?

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Dougie0047
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 Feb. 10, 2025 11:18:08
Hi, I'm currently doing some heightfield experiments, such as conforming a terrain to the surface of a road (polygon primitives). A bit like in Konstantin Magnus's tutorial here: https://www.youtube.com/watch?v=hWGCs4MLGqQ [www.youtube.com] Except, in my case I am generating masks before the vex wrangling, which gives me a bit more flexibility as to what to do with them.

This got me thinking though.. I'm wondering now about what is the most efficient way to work with height fields these days? The nodes that I use for creating masks etc. seems to be mostly hda's, with a bunch of other nodes inside them. So I curious if this impacts performance vs. vex wrangling? Also, since we now have the new COP's context, is it perhaps advisable to use this for height field manipulation, both in terms of flexibility, but also in terms of speed/efficiency?

Have some of you tried all these different approaches (nodes vs vex vs cops) and made some conclusion as to what the most efficient way to work is and/or what is the most flexible way?

Thanks,
Dag
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Technical Discussion » offsetting cross sections of sweep by curvature - how to?

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Dougie0047
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 Jan. 30, 2025 08:57:37
@Jikian - yes, of course! Thanks for the tip. I've done this now, and with a little bit of added logic it works perfectly fine and is controllable. Thanks again!
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Technical Discussion » offsetting cross sections of sweep by curvature - how to?

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Dougie0047
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 Jan. 29, 2025 07:16:14
Hi,
currently I am sweeping some road surfaces using polyline curves. I am using a curvature attribute to modify a @pscale attribute that scales the cross sections in the sweep if the road curve has steep curvature. This works just fine. However, it would be great if there was an easy way to, in addition, offset the cross-sections (on creation) such that the "inner" part of the road surface remained at the same curvature as the backbone curve, whereas "outer" part gets the scaled offset. This, in order to avoid that the inside gets too pinched when the turns are steep. It would have to work in such a way that it responds to left vs. right turns correctly. I am calculating a sign variable that could be used for this...
Currently most of what I already have is solved via vex, so a vex solution would be preferable, but I'm open to any suggestion.

Thanks,
Dag
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Technical Discussion » problem with creating new geometry overlaying old/original

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Dougie0047
88 posts
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 Nov. 13, 2024 16:35:22
@vklc Thanks for your replies! Ok,so basically we cannot do any generation from scratch in points, prims, or vertex modes. To bad. I was hoping I could cheat the system and generate "per primitive" even if the input is not geoself(), but input1. Thanks for the comparison btw. Have you tried a comparison to see what would happen if you generate the primitives when the incoming ones are on input0 and you delete the original ones? So, in other words, how much does deleting geometry impact performance? I always hear that deleting geometry can become very expensive, but I'm not sure what that means in practice.

Thanks
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Technical Discussion » problem with creating new geometry overlaying old/original

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Dougie0047
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 Nov. 12, 2024 16:35:56
Hello, I'm doing some small experiment with creating geometry, in this case polylines, that traces an original polyline. I would like to add n number of polyline primitives on a primitive wrangle's input1 (so input0 is empty), and fetch position data from this/those primitive(s), and then re-create an approximation of them with completely new geometry. I want the primitives to come in on input1 so that I will not have to delete them before or after creating the "new version". What is the right approach to this? It seems that creating the geo in detail mode or, when letting the original geo in on input0 is easier to get to work, but I would like to run this kind of code over primitives, potentially large amounts of them, and as said I would like to not have to delete any incoming geo - hence input1 and input0 empty.

The current code I have does not work, so I must be missing something. I have attached a hip file to this message so you can see the mini-setup with the code etc..

Hopefully someone can enlighten me

Cheers
Edited by Dougie0047 - Nov. 12, 2024 16:44:19
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Technical Discussion » How to best average out attributes over time?

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Dougie0047
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 Oct. 21, 2024 03:33:57
@tamte - ah, ok, see what you mean. Thanks!

@HristoVelev: This is interesting. I'll have a closer look at this later. On first glance I see that the article is quite math heavy. Do you also know of a more "pleb-friendly" reference? If not I'll work through it in my own time. From your short description above it seems to me that the practical solution would be to use the sop solver for this. Would that be a fair intuition?
Thanks again!
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Technical Discussion » How to best average out attributes over time?

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Dougie0047
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 Oct. 17, 2024 12:02:18
@tamte Had a look at the setup. This works really well! Thanks!
Just out of curiosity though, is there a reason why, in the setup, you make the @id multiples of 5? Or just habit?
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Technical Discussion » How to best average out attributes over time?

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Dougie0047
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 Oct. 16, 2024 15:53:24
Thanks tamte! I will definitely have a look at this asap
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Technical Discussion » How to best average out attributes over time?

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Dougie0047
88 posts
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 Oct. 16, 2024 03:34:33
@tamte Thank you for your reply.
I'm not quite sure what you mean though. How would I do this and what do you mean with N last value? The steps before the sim are that I first scatter some few points in a volume with a seed set to $F. So, that gives me 2-3 new points per frame. How can I keep adding an attribute to an array on this? Via a sop solver and then somehow transfer information to the points? I suppose what confuses me is how I can make the attribute stick when I'm constantly generating new points? And, when you say n last value, do you mean that I have to somehow throw out the other values in the array?
Thanks again
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Technical Discussion » How to best average out attributes over time?

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Dougie0047
88 posts
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 Oct. 14, 2024 17:40:29
Yes! That will work. Can't believe I did not think about that.
Thanks a lot
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Technical Discussion » How to best average out attributes over time?

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Dougie0047
88 posts
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 Oct. 13, 2024 15:14:06
Hi,
I've got a vellum sim where I would like to extract some of the attributes, say velocity for example, off of the simmed geo. I found that I can do this via the extract centroid node, so now I can get some attributes from a geo onto a point per piece. Fine. However, the attributes change their values from frame to frame too fast. So, I would like to further this by averaging out the information over three or five frames (1-2 frame before the current and one after), and then transfer or copy this back onto the simmed geometry for further use. But how? I cannot seem to find a good way to do this. What is the best approach?

The case is further complicated by the fact that the vellum geo starts out as copies to points over a certain range, so that I have an unequal number of points/pieces per frame for the first part of the frame range (until all pieces are in the scene).

Does anyone know a good answer to this?

Thanks,
Dag
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Technical Discussion » possible accuracy problem with the new clip sop?

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Dougie0047
88 posts
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 July 20, 2024 16:12:23
@tamte and @Aizatulin,

thanks for your replies! Much appreciated! I will look into your suggestions as soon as I can.

Dag
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Technical Discussion » possible accuracy problem with the new clip sop?

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Dougie0047
88 posts
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 July 19, 2024 15:55:42
@jsmack - thank your for your reply. Yes, I believe you are right. As the attached image shows, when visualizing the dist attribute I have the color match to the the point of clipping, and this is not at the same spot as the bool geo.
But then my question would be: what is then the best/most efficient way to overcome this?

Thanks,
Dag
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Technical Discussion » possible accuracy problem with the new clip sop?

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Dougie0047
88 posts
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 July 19, 2024 15:40:15
@Aizatulin - thanks for your reply, and for your modified example file. Actually a distance to the point projected along some specific axis is not what I want. In my own example file it is just set up like this for convenience sake and to be quick. In a more relevant example the curves would have arbitrary directions and would also not be just a bunch of straight lines. Most probably they would also not have to be flat on the xz plane.
Is your code easily adjustable for such a more realistic case?

EDIT: your original axis was the z-axis as you said. I've now added a mountain sop to deform the curves, and predictably the method fails to compute the distance correctly. Then I added an orient along curve sop, set to next edge to see if this fixes things, as in now I have a directional vector per point istead of a global one. This actually improves the result, but not enough. So I am still stuck with this interpolation issue or whatever it is. Any ideas?

Thanks,
Dag
Edited by Dougie0047 - July 19, 2024 16:15:07
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Technical Discussion » possible accuracy problem with the new clip sop?

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Dougie0047
88 posts
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 July 18, 2024 16:08:15
Hello there,
I decided to test out the new clip sop to see if, now that we can use attributes to clip, it will be a good new way to bool curves. I've attached a hip file with my test. In it I use the distancefromgeo node to generate a distance attribute and I use that attribute in the clip node. Everything appears to work, but if you zoom in on the result you can see that it is not accurate enough, meaning the clipping does most of the time not happen exactly at the intersection of the geo used to generate the distance attribute. For comparison the setup also contains an intersection analysis sop and with this I am able to generate points exactly at the intersection. All of this is easier shown than explained in words, so please check out the attached file.

Ultimately what I am wondering about is what is causing the lack of accuracy? Is it the clip sop?
Or, it is the distance attribute that is causing the issue?
If it is the attribute, what would be a better way of generating an attribute for the clip sop?
Or, am I on the wrong path here all together? If so, what would a better method to do what I'm doing in the example be? Provided that this solution would be fast and reasonably simple...

Btw, I do love the fact that we can now use attributes to run the clip sop with. I just wish I could get it to clip at exactly the right spot.

Thanks,
Dag
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Technical Discussion » a way to change point order through vex code?

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Dougie0047
88 posts
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 July 8, 2024 15:50:48
@animatrix
Thanks again for your reply,
I will have a look at your suggestion and see if I can make it work. Cheers

@olivierth
Thanks for your reply as well.
Using the sort node is not really what I need in this particular case, since I am planning to generate geometry with vex and will probably need to access point information and maybe sort things inside a loop etc.. Normally I do use the sort sop a lot though

Thanks,
Dag
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Technical Discussion » a way to change point order through vex code?

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Dougie0047
88 posts
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 July 7, 2024 10:23:22
Thanks for your reply animatrix.
Actually, I am planning on doing that - recreating the geometry in VEX. Specifically, parts of the geometry. The idea is to create new geo via vex, instead of deleting parts of the original geo.

The specific issue I have is that I would like to create geo for intersecting curves. Fine if they are just normal curves, but if I overlap a closed curve, say a square with a straight line segment I can see a couple of issues:
1 - how to recreate only the curves outside the closed curve? So not the intersecting segment inside the above mentioned square.
2 - where, on the closed curve, you have point 0 overlap with point npoint I get two new primitive segments instead of just one which is what I need. And my guess is that this has to do with point/vertex sorting, because at here the point number increases in opposite directions. Hence the original question.

So, I am very curious if there is an elegant solution to these problems? Especially inside the vex code.

Cheers and thanks again,
Dag
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