Dot per inch for render?

in 2.9 how to define Dot per inch for rendering
and how to calculate it now ?

happy cl

I don’t believe you can define DPI in Blender like you can in an image processor *cough*Photoshop*cough* as Blender always renders out in pixels (1920×1080px @ 72DPI, for example). In fact, all 3D apps work only in pixels.

That said, you need to calculate your final usage size. Is your image to be used online? On TV? Is your render going to be printed? Magazine? Newsprint? What’s the final size? Inches or millimeters?

Multiply/divide the height and width of your image by the desired DPI. Therefore a 5×7" image at 300DPI is 1500×2100px. Conversely, an HDTV image (1920×[email protected]) is 6.4&times3.6" at 300DPI.


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size will be 11 X 17"
and i already calculated at 300 DPI = 5000 X 3000 pixels

now my models has a scale axis to show distance and size
but when i use scale with every feet i almost don’t see it on rendered image
it is blurry and very pale

even tried with emission instead of diffuse and still blurry

at this DPI it should appear very clear i think!

happy bl

Cinema 4d does allow you to specify a DPI for your image when you render.

sorry i maybe completely wrong but normally when u set higher number for pixels under render settings, it wont result in a blurry image (in my experience)- maybe that texture is already low res?

where is the DPI for render in 2.9 preferences or elsewhere may be ?

i did a test with different objects size
and it is at the limit for the render

but also depends on the scene real size
i fit the cartouche around the scene

will continue later with other test

thanks guys

Dots per inch is meaningless in Blender. We can only specify pixels as an output size. If we could specify millimetres or whatever then we would require the facility to specify DPI.

Your 11" x 17" at 300 DPI is equivalent to 3300 x 5100 pixels, but those pixel dimensions could also be a 22" x 34" image at 150 DPI.

Blender does at least make it easy to do calculations in input fields. If you are working with inches all you have to do is enter the required dimensions in inches *300 to work out exactly how many pixels would be required. For those who work in millimetres it’s just millimetres *11.809

All of this is utterly meaningless unless you intend to print your render. A 5000 pixel wide image is a 5000 pixel wide image whether it’s DPI is set to 300, 150 or even 1

it does influence what the smallest object size can be if it has to be printed

in my test i had to lower the number of subdivision on my scale cause it came out blurred cause it was too small

and also for small size paper it normalcy prints at around 300 DPI

but DPI value is et in the file spec so it would be nice to include it in blender
but i cannot find that DPI setting in 2.9

i know where it is in 2.79 but not 2.9

happy bl

One of these images is 1200 dots per inch. The other is 1 dot per inch. Can you tell which is which?

What you seem to be talking about is something completely different. You are wondering about the size of objects in your scene and their clarity in your render. This all just comes down to relationship between their size and their distance from the camera and has very little to do with dots per inch (or pixels per inch).

i need to have it printable on a 11" X 17 sheet and see all the details
so DPI don’t change the render but might affect how it prints
i know it can be change in other soft like GIMP
would prefer to do it in blender then it is done

i think i found how to calculate the min size i need in blender

happy bl

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I worked in the print field for 21 years in a newspaper production department. We would have “rule of thumbs” about minimum sizes for things like line widths and type sizes which served us well. Generally we’d avoid going smaller than 6 point for type and 0.25 point for lines. Those were for type and lines printing in black. When you get into colour then you’d want stuff even larger… maybe 7 or 8 point for type and 0.5 point for lines. The reason being that a very thin line (like 0.25 point) is only 0.09mm wide (0.0035 inches). If that line is say red in colour then it’s not going to be printed with red ink. It’s going to be printed with a mixture of dots made up of magenta and yellow ink. The colour mixing is optical.

One thing you could try is this. Make up a document in Photoshop or GIMP or whatever, the same size as your final print output at 300 dots per inch. Add a variety of lines in different widths as guides near the centre of the document. Save it. Load it into Blender as a Background Image for your Camera and set it to front. That should help you judge whether anything (regardless of it’s dimensions in the scene or distance from camera) is getting near to being too thin or small for reliable CMYK printing or clarity. Toggle it on and off when not needed.


interesting these line width
i did a test file for some value that i’v uploaded
with some value from 12" down to 1 inches see earlier post

and as you said depends on
Camera distance
light set up for good viewing and contrast
and the minimum size of objects in scene

like engineering or architectural dwg size
Eng DWG size A - B - C - D - E
metric size -----
or architecture dwg size

i also made a Xcell file to calculate the real dim size you can put on different dwg size function of the scale for the DWG
scale on Eng Dwg is like 1/8" / Feet or 1/4" / Feet for imperial
equivalent metric has like 1/75 or 1/100

these dwg size are already define in the addon Print XYZ

do you happen to have a test file for these lines width
would like to test that with my set up for 11" X 17"

happy bl

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i did a building dwg for some one
and he would like to see the whole dwg on the screen and be able to see read
all the details without zooming in

i mean there are limit of resolution on screen too 96 pixels / inch for 1 K screen
so you have to respect the physical limits some how
cannot make miracles all the time LOL

some people don’t understand these limits !

happy bl

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Here’s a 17x11 one with 0.25, 0.5, 0.75, 1 and 2 point lines