ZBrushCentral

Document Size?

ZBrush Usage Questions
#1

I’m having some trouble understanding how to get the best quality render pass from ZBrush into Photoshop, with regards to dimensions.

I’ve studied a couple of tutorials but I end up being more confused than I started.

I’m looking to produce a photoshop file which is 160mm wide x 200mm high @ 300dpi. After creating a new doc in Photoshop using these dimensions, the image size conversion is 4800x6000 pixels.

From what I understood from the tutorials these figures (4800x6000) need to be input into ZBrush and then doubled. However you can’t go over 6000 in the Document size.

Are there any resources that explain the conversion clearly rather than a step by step procedure. I mean understanding why you’re doing something is half the battle when learning.

Any pointers would be gratefully received.

#2

Could anyone confirm that the largest document size in ZBrush would be 8192 x 8192. Converted for print (press) this would be 289mm x 289mm @ 300dpi.

Before rendering passes out of ZBrush the Document would need to be AAHalved to improve anti aliasing. I am assuming this would also reduce the final image in Photoshop to 144.5mm x 144.5mm.

I would really appreciate it if anyone could give me some feedback on these figures and whether I’m talking sense or complete rubbish.

Thanks

#3

You may have to bite the bullet and use a 3rd party renderer like Maya or Max.

#4

Thanks for your reply ioster. To be honest that was the reply I expected. I really can’t afford Maya, so I’ll just have to have a look around for another 3D package.

Thanks again.

#5

Depending on your needs, I know Max has a 30 day trial. Maya might as well. You could probably get a few models lined up and get them all rendered before the trial expired.

#6

You are misunderstanding the way the AAHalf option works. It is provided to give anti-aliasing for images that will be viewed at screen resolution; it is not necessary for images that will be printed. For those images the reduction in size from screen res (72 or 96 ppi) to print res (300 ppi) effectively introduces anti-aliasing. (The whole point of anti-aliasing is to reduce the ‘jaggies’ that occur on curved edges because pixels are square. The pixels at 300 ppi are small enough that this is no longer an issue.)

So, if you want to create a ZBrush document that is the right size for printing of high quality (i.e. 300 ppi) then you do as you did and calculate the pixel dimensions. The maximum that ZBrush can achieve is 8192 x 8192 which is equivalent to 693.6 mm x 693.6 mm at 300 ppi.

When you have done your ZBrush render be sure to export the image from the Document palette at Actual Size, NOT with the AAHalf button pressed.

HTH,

#7

Another thing, your math is out. You’ve confused pixels/cm with pixels/inch. For an image of 160mm x 200mm that will print at 300 ppi (or dpi - dots per inch - in printer terminology) you will need pixel dimensions of 1890 x 2362.

HTH,

#8

marcus_civis, you are a star. I think I’m getting my calculations wrong due to the conversion of 72dpi and 300dpi. I’m working out the pixel size in Photoshop at 300dpi. I’ll have another go and thanks to you I now know what 160mm x 200mm should be.

Would you agree that I need to work at double the size in ZBrush and then reduce in Photoshop?

Thanks again marcus_civis.

#9

No, there absolutely no need. Just export your image from ZBrush at actual size. In Photoshop, open the image and then change the resolution ONLY:

  1. Press Image>Image Size.
  2. Uncheck Resample Image.
  3. Change Resolution to 300 pixels/inch.
  4. Save the file.

Res.jpg

What you are doing is including (in the file) instructions to the printer to print the image at a set size. The pixel dimensions are not changed because you’ve created your document the right size in the first place (providing you get your math right!). ZBrush doesn’t include dpi data in the file header so you have to set that in Photoshop. There’s no other reason for using PS, unless you want to edit the image in some other way.

#10

Thanks again Marcus

You have just made one ZBrush user very, very happy and saved me a lot of money.
I am planning on carrying out some additional work in Photoshop.
I have to admit I didn’t know about the ‘Resample Image:’ tick box, no wonder I was getting confused.

You have made everything much much clearer.

Thanks again for your professional and concise feeddback, very much appreciated.

Mark

#11

Mark,

Im glad to help. :slight_smile:

The ‘Resample’ option is for when the pixel dimensions need to be changed. For example, suppose you have an image that is 945 x 1181 pixels and you want it to print at 16cm x 20 cm. As it stands, there are only enough pixels for it to print at 150 dpi at that size but you need 300 dpi. Switching on Resampling means you get the extra pixels. But it’s important to realize how resampling works. Basically Photoshop spreads out the existing pixels and then adds new ones in between, basing their color values on the existing ones. There are various Resampling methods to choose from but none of them will produce a good result for the doubling in size of my example, so for all but small upward size adjustments, Resampling is best avoided. It’s best to create your image the right size in the first place.

HTH,

#12

OK, I’ve just had a play and the final document fits the size I want, which is perfect. I’m just wondering if I can ask for one more bit of advice.
How do you fit the subtool to the document. In other words if the document size is 160mm x 200mm, how do you make the subtool approx 160mm x, 200mm without the canvas using most of the space.

I did try a couple of things but to no avail. As usual I suppose the answer will be really simple. I have included the results of my latest endeavors:

ZBrush-Document1.jpg

This would put the icing on the cake, thanks to marcus.

Mark

#13

That’s easy enough:

  1. Use the Zoom Document button (top right on the UI) to reduce the document so you can see it all.
  2. Draw your model on the canvas and press T to enter Edit mode.
  3. Press F or the Transform:Fit button to fit your model to the canvas.
  4. Use the Scale button (on the right of the UI towards the bottom) to reduce the size a litte so that it’s just how you want.
  5. Press 0 [zero] or the Zoom>Actual Size button and export your image (Document>Export). It’s not essential to press Actual Size - the image is always exported at actual size whatever the zoom unless AAHalf has been pressed.

HTH,

#14

Once again thanks Marcus.

Brilliant. Easy when you know how. I now understand much more about scaling in ZBrush.

Thanks again for sharing your patients and knowledge.

Mark