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I modeled a high poly gun and uv unwrapped it. I then duplicated the object and removed a whole lot of edge loops to make it lower poly (3500 tris for the high poly gun to 350 tris for the low poly).

The question is how do I bake the normal map? I am in the blender render and have "selected to active" checked and the baked normals come out all strange with holes in some faces.

I think it might be because the uv unwrap for the low poly is different than for the high poly maybe? Any tips on how to correct this? The UVs and normals is the last thing I need to figure out...

normal map high poly uv enter image description here

EDIT

Folloed the guidelines and BAM these are my results: Normal Map and the loweres object with the normal texture node attached to the displacement output rendered.

Thank you so much!!

fixed normal render with normal map applied

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It's not actually required that you unwrap the high poly mesh for this operation to work, only that the two meshes be in the same location when you do the baking. Development of aberrations around corners is a common problem with normal maps. Cycles allows baking now and has a cage function that may help.

Take your low poly model and make a duplicate of it. This is going to be the cage object. Using Atl+S increase the size of the cage object to be slightly larger than the target object. You may have to do a little tweaking to the cage to ensure that it has an even surface around your target object

Switch to Cycles Render and create a new material for the target object.

Create a new image to act as the normal image

In the node editor go to the material for the target object and create an image texture node and load the normal image you just created into the node. The node does not have to be connected to anything it just has to be there.

Go to the Render tab in the properties window, go down to Bake, select Normal in Bake Type, set Space to Tangent, check Selected to Active and Cage, and select the cage object in the object selection window

Select the hi-res source object followed by the lo-res target object and click on the Bake button.

If all goes well you should get a much different result than the one you're getting now.

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  • $\begingroup$ it worked perfectly! thank you so much! If you look at the render could you tell me how to get rid of the traingle lines at the top front part? and I assume for the edginess of the back I need more detail on the low poly model since normal maps can only do so much? $\endgroup$
    – Killerpixler
    Aug 14, 2014 at 13:13
  • $\begingroup$ let me see if I understand this correctly: for future reference I should have a slightly smaller low poly object and from it make a cage which is bigger than the high poly and then have the high poly sandwiched inbetween? $\endgroup$
    – Killerpixler
    Aug 14, 2014 at 17:27
  • $\begingroup$ The cage has to be larger than the high poly object. The low poly and high poly can be the same size. The cage itself acts as a boundary for the ray casting. Cages are most useful when trying to make a map for an object with sharp corners since it will help create a smooth transition around the edges. $\endgroup$
    – Hellfireboy
    Nov 29, 2014 at 14:59
  • $\begingroup$ > Using Atl+S increase the size of the cage object to be slightly larger than the target object. Alt + S is clear scale, what do you mean? $\endgroup$
    – clankill3r
    Mar 27, 2016 at 22:49
  • $\begingroup$ Does the cage have to be uv-unwrapped? For me it keeps saying no active image found (it is even highlighted in orange in the node editor...). $\endgroup$
    – clankill3r
    Mar 27, 2016 at 23:12

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