Causes of Black Screen or Failure to Render

[Kimberly Rodgers]

Looking to find out why when I hit render the screen  pops up and it does not render. It did once but then that was it.  I have the full version and have rendered another project with this program and the failure to load the image was never and issue.  Any ideas? Thanks

[Kimberly Rodgers]

Okay so it does start to render, after 5 minutes it will load a very low quality, I have it set to 3000 pixels because it was loading so slow. Any suggestions?

[akinlolu olugboji]

Try using any of the lighting preset and keeping the resolution at say 640 x 480 for a start.

[Peter Milner]

Start with a fairly simple model and simple materials.
In fact I find it's the materials that slow rendering down more than anything else.
What is the speed and memory of your computer?

[Kimberly Rodgers]

It has 8 RAM, and 2.53 GHZ with a turbo boost up to 3.00 GHz. My harddrive has 450 GB, 329 GB free

I got it to render in high res last night but it is still taking a while. (pass 13 after 7.5 hours)

When I did the raytrace I had it set to 640 x 480 and that would take forever so when I rendered in highres it is kind of like I am rendering blindly because the low resolution rendering would not load

[Roy Hirshkowitz]

Send the drawing if you can-- use Support->Upload a File and I'll take a quick look to make sure nothing's wrong.

In general, 640 x 480 will be much faster than a "hi-res" version.

[Peter Milner]

If you only have one processor, that will certainly slow things down. Doubling the number of processors will roughly double your rendering speed.
Roy uses a 12 core machine for development as he needs to see results quickly.
I sometimes have to render at around 5000 x 3500 for 200 passes. These I do overnight on an 8 core processor, or even over a weekend.

[akinlolu olugboji]

In addition, if you have access to more than one workstation the farm can help speed things up. Git it a try.

[Kimberly Rodgers]

okay thank you

[Roy Hirshkowitz]

So I did take a look at this one-- what you've got is an incredibly slow rendering. As Peter suspected, it's due mostly to materials. You can easily verify this by going to Render Settings and unchecking the box marked Use Materials-- at that point the thing will zip along as expected.

I haven't had a chance to examine this very closely-- but my guess is that the problem with your materials is that almost all of the surfaces in your model are slightly reflective. This is causing a huge rendering overhead in terms of additional reflection rays, for not much visible benefit. Two choices here-- use the Path Tracer which is not as sensitive to this (it may take too long to converge) -- OR-- in the Material Editor set the Reflection Shader to Glossy for all those surfaces which are only slightly reflective to prevent ray casting. More info. on reflection shaders is here.

*********

A couple of other points I noticed right away in your model

1. The pendent lights are configured so that both the globe and the shaft will glow-- may not be what you intended.

2. You're using an image as sky light-- probably not a terrific idea. Leave the sky alone (go back to defaults) and change the visible background if you must. This article explains how to combine interior daylighting and lights.

3. Consider using lighting channels if you're going to use both daylighting and artificial lighting. It's more fun.

[Kimberly Rodgers]

okay thanks! I changed two materials to glossy and it is already rendering much faster, and I set it to path tracer as well. Switched off the other things that you mentioned. Thanks for the help.

[Roy Hirshkowitz]

FYI-- the glossy switch doesn't matter if you use the path tracer. It can matter a lot for the standard engine.