Hello to all,

I was doing a bit of learning, and I watched 2.takes_rops tutorial movie,
everything went fine until I made a shadow pass take. Every time I try to launch render I get this error:

mantra: Singular matrix detected “/obj/grid_object1”, object ignored

and output is black frame with no shadows in alfa.

I went back'n'forward few times without success.

Things I noticed that are different then in the video are:

In shadow_pass mantra node I have Expression stack error

Same error shows up in grid_object1 node

here's a file:

it is v9.0.803 on winxp

I don't know what is the reason of this behaviour, maybe there were some changes in Houdini. But in general

mantra: Singular matrix detected “/obj/grid_object1”, object ignored

means that object has a bad transform matrix applied so mantra can't evaluate it. It seems in this case that expression error in shop_path causes Houdini to stop exporting proper object to ifd file. So there is no valid object in ifd - although it's was mentioned.

All I did is reapplying shops for all error prone objects - I had to also recreate some of them and it woks fine now. Still have no idea why it's like that.


hope this help,
sy.

There seems to be a bug with the Shop/material path.

I can get your shadowmatte to work if I use the menu selector and choose your material via the path /obj/shopnet1/material1, no single quotes.
The Shopnetwork node will still show an error but the render is correct.

You perhaps didn't create the material correctly. I recreated the shadowmatte material by calling in the vex shadowmatte node, then Shift-C to collapse it into a material, I also promoted the parameters up to the material although that isn't essential. This cleared the error from the Shopnetwork node.

thankz people
indeed it works now… I guess I made some click-mistake that I wasn't aware of…