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I'd like to render a normal map for an entire scene (for a large background for an isometric game). I tried exporting the "Normal" pass of my render layer, but it's not quite right. Here's what I get from a cylinder:

Rendered

For comparison, here's more what I (not to mention the game engine) was expecting:

enter image description here

I've seen tutorials on normal maps, but they are all about baking one object's geometry onto a simplified model. Is there an easy way to render a normal map for an entire scene, to line up with the standard combined render?

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    $\begingroup$ Guessing from the colors, your actual result might be in object space, but what you want is tangent space. $\endgroup$
    – CodeManX
    Jul 14, 2014 at 12:52
  • $\begingroup$ The normal pass is VERY different from what you would get by baking normal maps. $\endgroup$
    – GiantCowFilms
    Jul 14, 2014 at 16:46
  • $\begingroup$ @CoDEmanX I thought it was something like that, but I don't think I want tangent space, because then wouldn't anything due to geometry rather than material appear flat? $\endgroup$
    – andyvn22
    Jul 14, 2014 at 18:10
  • $\begingroup$ It would appear flat where the low poly object and the highpoly object have the same tangent, but the details where the high poly object is different will show up. $\endgroup$
    – gandalf3 ♦
    Jul 14, 2014 at 20:51
  • $\begingroup$ But in this case there is no low-poly object. $\endgroup$
    – andyvn22
    Jul 15, 2014 at 2:22

2 Answers 2

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Got it! As I thought, Blender's normal pass contains exactly the right data, but it's not in the right format. From a video intending to use the normal pass in After Effects' "Normality" plugin, I found that it's easy to convert Blender's colors to the standard colors using the node editor: Normal Fix (This node setup is for Blender Render, not Cycles. For a Cycles solution see this answer.)

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    $\begingroup$ In current versions (I'm using 2.71) of Blender, the rendered normal map colours will still not be correct. This is because the image will most likely have gamma correction applied to it (yes, even the normals) and will look too light. To fix this, open the 'Scene' tab in the properties pane and change 'Render' in the Color Management dropdown to 'Raw'. $\endgroup$
    – MrFlamey
    Aug 27, 2014 at 6:37
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    $\begingroup$ In addition, if you are doing this with Cycles, you don't need the invert node for some reason. However, blender internal render is MUCH faster if you only need the normal. $\endgroup$
    – MrFlamey
    Aug 27, 2014 at 7:26
  • $\begingroup$ I agree that one looks more correct than the green-red one, but how do you quantatively say it is indeed correct? I am trying to recover the normal vectors from the normal map and not sure if I am going that correctly. $\endgroup$
    – Sibbs Gambling
    Oct 8, 2016 at 16:01
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    $\begingroup$ @SibbsGambling: It's definitely a bit of a guess, but given how correct it looks (everything looks perfect to my eye in all my tests that use these normals) and the not-too-magic numbers that appear in the node editor, I'd wager it's spot on. If you're having trouble reading the vectors, you could start with a known-correct example texture & normal map from a website if you're worried that your Blender work is the issue. $\endgroup$
    – andyvn22
    Oct 9, 2016 at 11:52
  • $\begingroup$ @SibbsGambling You can compare your results to the normal Matcap. If the colors are the same as when viewed through that Matcap, they’re correct. $\endgroup$
    – Mentalist
    Jan 16, 2018 at 15:49
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Really old thread - i know - but you can achieve that (at least in blender 2.8) by switching from Cycles/Evee to Workbench.

in Rendering Tab -> Set Render Engine to "Workbench" and then: Rendering Tab -> Lighting -> select MatCap -> select "check_normal+y.exr" as Studiolight and viola!

i hope that helps

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  • $\begingroup$ Probably pushing my luck, but if anyone has figured out how to do what this comment does BUT also factoring the normals in the object material itself I would be very interested ty $\endgroup$
    – Thomas Harris
    Jul 10, 2022 at 17:22

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