View Full Version : rendering 36"x36" photo

11-21-2013, 04:52 PM
I rendered out a 36"x36" image with a print resolution of 300 pixels/inch. I increased the render render mode to be a time limit of 24 hours. I also sent it to the queue. When I looked at the photo today, it was extremely blurry and looks worse than any small image that I have produced before. Any ideas of why and how I can change this?

11-22-2013, 10:30 PM
Ok so you have render a 36x300= 10800x10800 image?
It's REALLY HUGE, because it means more than 100Mpixels... Not sure that your card had accept this size... What is your hardware?
Personnally, I've a GTX 580 with 3072MB of VRAM and after 50Mpixels, it was just impossible to render...

What you can do is to render by region, so maybe, it could works (example: 4 Render Region of 5400x5400).

11-23-2013, 10:02 AM
And about "language", you can forget the 'inches' and 'dpi' in the case of 3D calculation. The important thing in the numerical calculation world is the number of pixels, only that. The dpi and formats (A4, A3, etc.) have only importance in the world of printing. A computer works with quantities of pixels to calculate (render) or display (realtime).

In other words, doing a rendering of 2000x1000 @ 300dpi, for example, will not be longer and complex to calculate than a rendering of 2000x1000 @ 50dpi ;)

11-23-2013, 06:24 PM
Also, what do you mean by "blurry"? Is the image also blurry if you render a small version? How are you viewing the image when it looks "blurry"?

More info will help.


11-26-2013, 06:38 PM
I've retested, in fact, it work until 500Mpixels for me... So, I don't know. But as David says, what do you mean by blurry? With noise, no?

11-27-2013, 01:40 PM
Do you have depth of field turned on? I did a render a while back with DOF turned on and it looks fine in your viewport, but once it's bigger you find that it's actually blurry. For big renders I suggest to leave that turned off and just do it in Photoshop if you're looking for a subtle effect. There is also a Great trick for large renders to fool 99.9% of people. Render it at the right DPI for the distance first. For every 3 feet away, reduce DPI by 25% or so. You be the judge, but at 6 feet+ you can go down to 50dpi for most renders. 3 feet will be closer to 75-100, and it quickly goes up as you get closer.
The big trick is you can get away with reducing those numbers by as much as 50% if you scale the file up in photoshop, then apply graphics or other sharp details at full resolution. People focus on those small details and ignore the other pixelation. If you have highlights that go all the way to white this will not work. But it works. I applied some vector graphics to a console and had the actual render going all the way down to 25dpi. People didn't notice a difference between 50, 75, 100, and 150. This test was done at 3 feet.

Your render is also only as good as your worst detail. Rendering something at a higher resolution might also just show off certain elements that are perceived as fake. One example of that is a room. The edge of the floor is Never straight. If there is carpet you'll have some bits of the carpet that pushes up on the wall. The baseboard should have some gaps here and there. Unless you modeled those details in, just render it at 150dpi, then scale it up in photoshop to add in those tiny defects.

Also regarding maximum size: you can get even higher with CPU only if you have enough memory. I think it still renders out each chunk in 4000x4000 pieces, but the whole scene still has to load. And the rays still have to bounce to the rest of the scene. I tell everyone here to size things down in 4k increments as much as possible. Test it out. Render 8000x(xxx) on a render. Then render out 8200x(xx). It will take more time for that extra 200 than you would like. So by dropping down to 8000, you'll save yourself some time. It's better to have less noise in your image than more resolution, so it's a balance.

12-03-2013, 05:26 PM
This is an rendering that went for 24 hrs 36"x64" (which gives it a resolution of 19200x10800)with a print resolution of 300 pixels/inch: https://www.dropbox.com/s/0gzrv545tfzhp2x/ezpal2.jpg

When zoomed in it is very pixelated and it is overall not as clean and clear as I would like. This will be printed at 36"x36" and people will be looking at it up close so I need as much clarity as possible.
I will try a lower print resolution. If rendering it by region is better, how would I go about doing that?

Thank you for the help so far

02-07-2014, 05:54 PM
I've had the opportunity to render a full size car for a client. Because the dude doing the plot had a limit for his printing server I reduced the dpi down to 72. This took the file size down to only 184.2 megs and the file print size to 14904 X 4320 (207" X 60"). My client gave me a copy of the plot and it was very clear, it's hanging in my garage right now. The render took about 4.5 hours on my box. I don't know if this helps at all, but I'd recommend reducing the dpi. Here's a look at the results... https://www.dropbox.com/sc/yrjjpkd91oivzin/Dd6FlrlRR8