Hi I just started using Houdini and whenever I add an object it appears in all black, so I can't see any details just a black blob. Is there a simple way to fix this?? Also when i render any of these images i just get a black picture there is nothing to be seen.

Two main causes for black rendered objects:

- light inside the object with shadows on
- Geometry has zero length point normals

For lights, if you actually have no lights in your scene, mantra will build a headlight for you. If you do have a light in your scene (absolutely highly recommended!!!) then make sure that the light is in the proper place. Easiest way to do this is to look through the light (accessed via the upper right yellow cam viewport menu), lock the view to the camera by pressing the lock icon in the upper right hand toolbar and then adjust your light with the view controls until it is actually contributing lights to the objects

As for normals, if you have zero length point normals on your geometry, it will render black both in the viewport and the render. Normals are used to determine the light contribution on the surface. To fix this, append a Point SOP and in the Point Normals menu option, choose “No Normals” to remove them.

Hope that helps.

Thanks for the reply.
I don't think it's the lights as I am positive I have them set up right so I'm assuming it would be the normals then.
I am really new at this though and have no idea how to append a point SOP any quick hints or a link to a tutorial? I haven't been able to find a useful one!

Appending a Point SOP node or any geometry modifier operator SOP is key to working with Houdini. Have a look at the intro video on Node Workflow here:
http://www.sidefx.com/index.php?option=com_content&task=view&id=1868&Itemid=347 [sidefx.com]

Here's how you append a Point SOP. Double-click dive in to the object. You should see one or more SOP geometry operators wired together with one node that has a blue flag on it. That's the display flag and determines which operator sends what geometry to the viewport and the renderer.

To append a new operator to the last SOP geometry node, press and hold the Right Mouse Button (RMB) on the bottom output arrow “tab” and from the list, start typing
p o i n t
and when you see the Point SOP in the list, select it and hit enter.
Now you have appended a Point SOP.
Next move the display flag to the Point SOP. As you become adept at working with SOP geometry networks, managing the display flag is critical.

You can query the cached result of each Geometry SOP node by holding down the MiddleMouseButton (MMB) on the icon on the node. You can see any normals on the geometry.


Having said all that, please post your scene file if you continue to have issues and we'll have a look.

Thank you. Unfortunately that was the first thing I tried when you said to append a Point SOP but for some reason the option for Point SOP doesn't come up when i look at the list.

I've posted the file. I was working on one of the tutorials on the website. With the lights I can actually see the objects although the lights behave oddly but when i render it it is still just a black picture.

I was able to render a scene to mplay by hitting the render button in the viewport's left hand menu at the very bottom. The icon with the film can icon. Hit that and choose mantra to render. Mplay should pop up and you should see a rendered image.

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I highly recommend adding a Mantra ROP Output Driver for any scene and use that to control Mantra rendering.

From the main menu at the top, go to Render >Creat Render Node
and either choose Mantra or Mantra PBR. Mantra PBR uses physically based rendering btw.

Now there are several ways to trigger a Mantra render.
- Easiest way is on the lower left of the viewport, there are two icons. The very bottom icon will show you all the various mantra render options. Choose the mantra1 output driver you added above.
- From the Mantra output driver found in /out directory, select the node and hit the Render button on the parameter interface.

Given that you are very new to Houdini, I highly recommend you switch to the Technical Desktop.
Main Menu: Window > Desktop > Technical

The Technical Desktop always has the Tree View on the left side which shows you the entire Houdini directory structure. Houdini is an actual file system in memory. The funky thing though is that nodes can both be an operator AND a folder container. Objects are that way and live in /obj. With the Tree View, you shouldn't get lost and can find your way around a lot faster.

With the Tree view readily available, you can easily see where you land when you use the various shelf tools. It's always easy to get back to /obj and see your scene objects after going to /out to inspect the output drivers that you will invariably create when you start getting in to takes and render passes.

Hope that helps a bit.

Alright well I must have a problem with the program itself if the file is fine as still when i do exactly as you said (i tried both ways) I get the following outcome.

That is not what I am not seeing at all.
I suspect a hardware graphics card issue.

Hardware? Graphics?

Alright well thanks anyways I'll look into that.