Partial Image In Render Output Window

HaroldL · October 14, 2017, 12:57:43 AM

This is an issue that first came up at work. We needed a 40 inch square image rendered out for a poster. So I set the image size to 40 x 40 at 300 dpi and hit the Render button. The render output window came up and started to paint in the image - all except the bottom 1/3 of the window. The image never completed. I contacted Support and provided the ksp file and, as usual the issue did not repeat for Ian at support. Never the less, we were able to render out the image at size without it being cut off at the bottom.

So, my home computer I repeated the same steps, loaded in a model, set the image size to 40 x 40 inches @ 300 dpi and hit the render button. Then I sat back and watched as the render output window painted the image all the way down to where it stopped, leaving the bottom 1/3 blanked out, just like at work.

The follow up from Ian at Support told me to update to the latest version. At work I'll have to wait for the IT folks to do the update. but at home I downloaded and installed the latest v7.1.51. Once installed I loaded up an model, set the image size, hit render and watched as the same issue repeated itself. A screen shot of this is attached.

At some point I clicked on the Effect Panel Icon and noticed that all the tools were greyed out but it had some text stating that the image was downscaled due to the render output memory limit, I've attached a screen grab of the text. It indicated that the memory could be increased in the Preferences>Advanced tab. So I bumped up the memory from the default of 256 mb to 512 mb and gave the render another shot. Well, no luck there either, this time the render window just came up all white and after waiting a while it didn't appear to make any effort to show an image. (That's the big white image attachment.)

So, Monday when I'm back at work I'll get a message off to Ian in Support and let him know what I've found out so far. Then I'll have IT install the update, just to keep current, but I don't expect the issue to go away. We don't normally create large images, the vast majority of the renders will only be 7 or 8 inches square although there may be an occasional render that is larger. The render output window issue never showed up until this 40 inch monster came along.

So, some questions here:
Has anyone else experienced an issue like this with large renders?
Is there a limit to the render output memory?
How do you calculate what the memory should be for a given size image?

My home system specs are: i7 4710HQ @ 2.50 GHz; 12 GB of 2.50GHz memory; 64 bit Windows 10 Home.

Rex · October 16, 2017, 03:55:17 PM

Hi Harold,

I can reproduce with your scene, thanks for sharing. We will investigate.

In the meantime, you should be able to render fine using Custom Control instead of Max Samples/Time.

HaroldL · October 17, 2017, 06:04:20 PM

Thanks Rex.
Can you give a little more information about the Preferences setting for the Render window memory limit? It sounds like it should be easy enough to figure out, but it doesn't make sense, well at least I can't figure it out. Are there any guide lines to follow when adjusting the memory?

Rex · October 18, 2017, 10:00:46 AM

Hey Harold,

Actually this preferences setting has nothing to do with the error you're seeing.

Over a certain resolution the image is split into regions to save on memory usage. In 7.1.51 the image should actually complete if you let it run.

Can you confirm this? Perhaps test it out with a low samples value so it renders faster.

Thanks,
Rex

HaroldL · October 18, 2017, 05:56:57 PM

Ok, so I set up the image to render out Max Samples at 16. Clicked off to render in the background and in the render output window it filled in down to about the same 2/3 of the window. I let it set and render for just over an hour. Samples counter got to 16 sat there for a while then reset back to 1 while the remaining bottom of the render output window filled in. As I write this it has been cooking now for 1:22 and change and the samples are up to 5, I assume for the bottom portion of the render.

I am attaching a screen shot of the render window taken just after it filled in the bottom portion. The red line is where the cutoff was.

Quote from: Rex on October 18, 2017, 10:00:46 AM
Over a certain resolution the image is split into regions to save on memory usage. In 7.1.51 the image should actually complete if you let it run.

Can you confirm this? Perhaps test it out with a low samples value so it renders faster.

Thanks,
Rex

Sooo... What I am seeing is the splitting of the image into regions?

Rex · October 18, 2017, 07:27:54 PM

Yes that is exactly what you are seeing. I'm not entirely sure how the region size is determined but the larger the image the more regions.

The regions will render sequentially from top to bottom. If you are using Max Samples then the value set will be reached by each region before moving on to the next. I do see there can be issues with Max Time due to the requirement of at least 1 sample per region.

HaroldL · October 19, 2017, 06:01:40 PM

Thanks Rex -
I checked in the manual and while it does say that larger images are downscaled when the render window memory limit is reached it doesn't say anything about the render window only displaying the region being rendered. Maybe some clarification in the manual is in order.

I'm still baffled by the blanked out (white) render window when I tried to adjust the memory limit though.

Rex · October 20, 2017, 09:49:06 AM

You are correct that it is not included in the manual. I will make a note to add this in.

In order to make clear what is happening we will add some info to the status bar for the next update i.e. "Rendering (488 KB, 5:17 min, 1 of 2 tiles, 2 of 64 samples)"

As for the white render window I'm not sure what is happening here. I set my output window memory limit to the max of 1024 and I see the render correctly, granted I have 32GB of ram.