Modeling - A Few Oddities

[Jens]

Today I did give the modeling tools of Houdini a try and after a rough start I pretty much enjoyed it. A few things seemed a bit odd however.

Crashes: I have version 8.1.704 and was running it on win x64 and on win2k3 (both intel dual core). It crashed quite a few times when I was in the middle of an editing operation. Are other users experiencing this too / does it runs very stable on other OS / CPU combinations? I only noticed the frequent crashing when working with SOP's.

Snapping behaviour: Although I disabeled the snapping options sometimes when modifying a point in an ortho view the point would snap to a reference grid. Once this happened any point I tried editing was snapping on that grid. Is there any special short cut I might have accidently hit ? In all other view panes the bevaviour was as usual. (Working in front view (xy) it snapped to the xz pane with constant z value at 10, y was 0.. could only move points along x axes). Restarting Houdini solved the problem for me, but this happened several times (hence my guess there is some shortcut).

Workflow: I'm used to select the edges, point, primitives first and choose the operation afterwards. However once I choose an option Houdini will promt me to select geometry to transform anew (and reselects the last edited selection). Is there some small tag I can check so I can preselect the edges first and choose the operation afterwards?

NURBS: Arrgggs.. I didn't expect Houdini to offer tools identical to Catia / ProE but either I'm missing something or this is an area that has been pretty much neglected. Is it a matter of getting used to them simply?

Other then that I have to say I really enjoyed the polygonal modeling tools. I only missed one thing here.. can I add a weight on edges to selectively change the smoothing bevaviour when rendering as subd surface / using the subd sop?

Cheers

[MADjestic]

Other then that I have to say I really enjoyed the polygonal modeling tools. I only missed one thing here.. can I add a weight on edges to selectively change the smoothing bevaviour when rendering as subd surface / using the subd sop?

Cheers

Sure - try Crease SOP.

Btw. Crease SOP (as you can see that from Help) – won’t work on ‘render as polygons as subdivision’ – as you could expect from Renderman, for example. This is due to the licensing issue with Pixar.

Concerning the stability issue under the windows box - prolly this is solely my opinion, but it seems to me that SESI is strongly aiming at Linux boxes - I really rarely experience any crashes when modeling in SOPs. (as a matter of fact I had none while working on my bridge shot – lots of editing and cookies operations, subdivisions and others. I use 8.1.780 build however. ) As far as Windows is concerned – I do experience Houdini crashing from time to time. So maybe this is not a very suitable solution for you, but I strongly recommend you to become a Linux convert as soon as possible You won’t regret this when working with Houdini.

As far as your modeling experience is concerned – I am sure you should’ve noticed the tool deck docked on the left – there you can see points, vertexes, edges, faces, etc. that are used when different operations are applied. The typical workflow is to press Tab (over the viewport/network viewer), choose the Edit SOP and press 2 (to choose edges selection – or whatever you want). Then simply press q to repeat the previous OP selection (this won’t add any extra Edit SOPs – but reuse the existing one instead, though you certainly can add as many Edit SOPs as you want) – this will also have edges selections turned on (from the last OP – you see?)

rrr

[Jens]

Ah thank you. I saw that crease SOP just now, most unfortunate Mantra won't evaluate it.

I prefer Linux myself, no need to convince me, however there are other programs I need to use on a daily basis and there exists no win version and the windows emulation on linux isn't all perferct. Wine has improved quite a bit, but at university most programms are usually written for Solaris or Win. Hence I often end working on win

On the workflow thing.. currently I'm doing it just as you describe however sometimes I press 's' select a few things and want to start operation XYZ based on that selection. However then this selection gets lost, the objects that were modified the last time get selected and I have to redo the selection. Having to choose the OP always in advance is likely just a matter of getting used to, but my guess is that there exist some option to change it. No ?

[old school]

Hi Jens,

I use Houdini to do modelling quite frequently in both Windows and Linux. I don't experience the crashes you do. I do crash one in a while though. Did they occur with Edit SOP operations specifically? The more info the better then send it off to support. As usual, it is best to stick with recent builds.

Have to test SOPs using the 's' key and selection-action workflow. I predominantly model action-selection myself. I am not surprised that some SOPs ignore the viewport selection and use the previous SOPs selections. The NURBs/Bezier centric SOPs?

Crease support in Mantra hopefully will be in H9. Creases are supported by the Subdivide SOP in H7 and H8 though.

The snapping behaviour you describe is strange. The shortcut to turn snapping on and off is ctrl-j. Not an easy mistake to make. Turning the snapping on and off is funky in H8. The menu you pop up has a toggle on it. That is the only way to turn it on and off other than using the hotkey ctrl-j (or remapped key). Opening the Snapping dialog and choosing a snapping priority isn't enough to turn snapping on and off. Confuses some people.

NURBs Modelling is not that refined with the interactive viewport workflow. Focus was placed mainly on the Poly Modelling tools and their development. A reflection of reality really. Polys with sub-d's are the current reality for modellers. NURBs and Beziers still have a vital role in my modelling workflow but only for certain types of tasks. I sometimes use NURBs and Bezier curves to create outlines of some props as guides. I sometimes create NURBs patches in areas I know I will be reworking a lot. Keep things as procedural as possible before I convert to Polys to add small details and blend in to other poly patches. As good as pasting and trims are, they are quite expensive to evaluate in the viewport and the limited precision in Houdini SOPs makes these types of operations fussy. I have heard on numerous occasions that Maya is fussy with many NURBs operations as well so we aren't alone here. Not making any excuses either. Booleans with NURBs (SurfSect SOP) in Maya and Houdini require fiddling to work. You will notice these transitions in Mantra.

Poly modelling is quite a lot of fun. As much fun as building a nice procedural effect. There are so many approaches to try. Different topology approaches as well. Many create beautiful patterns when pushed through a SubDivide SOP.

[sibarrick]

Hi Jens,

I use Houdini to do modelling quite frequently in both Windows and Linux. I don't experience the crashes you do. I do crash one in a while though. Did they occur with Edit SOP operations specifically? The more info the better then send it off to support. As usual, it is best to stick with recent builds.

I seen a lot of crashes with using the edit sop, but purely memory related - on windows - often when sculpting a big mesh the memory usuage goes up very rapidly with each brush stroke and there is nothing you can do to release the memory used except restart the hip file. If the memory goes over 1Gb bang it crashes.

[B.Walters]

I seen a lot of crashes with using the edit sop, but purely memory related - on windows - often when sculpting a big mesh the memory usuage goes up very rapidly with each brush stroke and there is nothing you can do to release the memory used except restart the hip file. If the memory goes over 1Gb bang it crashes.

OH MY #&*$( - That explains soooo much! Thanks!!

On the workflow thing.. currently I'm doing it just as you describe however sometimes I press 's' select a few things and want to start operation XYZ based on that selection. However then this selection gets lost, the objects that were modified the last time get selected and I have to redo the selection. Having to choose the OP always in advance is likely just a matter of getting used to, but my guess is that there exist some option to change it. No ?

I do believe the order of selection in H9 is reversed... Which, was to my dismay at first, but I'm slowly getting around to actually preferring it. It will also definitely be better for users who are switching from other packages though, as that's the more 'standard' order for applying operations.

[edward]

On the workflow thing.. currently I'm doing it just as you describe however sometimes I press 's' select a few things and want to start operation XYZ based on that selection. However then this selection gets lost, the objects that were modified the last time get selected and I have to redo the selection. Having to choose the OP always in advance is likely just a matter of getting used to, but my guess is that there exist some option to change it. No ?

Er, you're doing it already. You press 's', select some geometry, then hit Tab > whatever operation. Do you have an example series of steps that show how this selection gets "lost" ? Do you have Secure Selection turned off or on? Are you in SOPs or Objects?

[Jens]

Er, you're doing it already. You press 's', select some geometry, then hit Tab > whatever operation. Do you have an example series of steps that show how this selection gets "lost" ? Do you have Secure Selection turned off or on? Are you in SOPs or Objects?

Im using SOPs.. e.g. polyextrude on edges. However I have Secure Selection turned off (I have just checked and with secure selection turned it keeps the selection). I guess I was looking for that behaviour without secure selection (having secure selection turned on when doing often the 'edit' operation seems more of a slow down since you need that one extra click). And yes it's just one extra click away to turn off secure selection.. so it's more me not being used to that workflow. Having in the 'edit op' dialogue (the one you get when pressing ctrl) some check box to automatically disable secure selection / save preferences operator sensitive on the selection modi could be nice. For the select operation it would be nice being able to set as preference to automatically set the 'display points option' if your selection type is set to points.. show normals when selection type is 'primitives' etc. My guess is that such preferences would make it more intuitive for people new to Houdini.

But overall, I'm more and more impressed by all these many neat features of Houdini's modeling tools as I learn to use them better (some of them just seem a bit hidden, until you know about them).

Concerning the crashes: the odd snapping behaviour occured again once around 1gb ram was used and shortly afterwards Houdini crashed. I could reproduce it on two systems (the high crash chance once around 1gb ram is used). Seems independent of the available physical memory (occured both on my 4gb eec ram system as well as on the 1,5gb one).. and no crashes with linux on a 512mb ram notebook. On windows it helps to close all other memory consuming programs since it doesn't seem to matter if Houdini alone takes up most of the 1gb ram or shares it with other programs.

[edward]

Regardless of your physical memory, 32-bit processes on Windows only have 2GB of "virtual address space" memory to work with. This 2 GB is further reduced due to loading of various system DLLS, Houdini and it DLLs, etc. When all is said and done, there's a lot less of memory available than you think. If you're modeling and getting into out of memory crashes, the best thing to do is to lock your last sop, save your .hip file and then restart houdini.

[stu]

I run into this limitation myself and I'm looking forward to the new OS next year which should remedy the problem.