Adding details on models in Zbrush, then bake a normal map?

Abracadaniel

So I have a weapon that I want to add some 3d decals/details on. So far I have been able to sculpt new details and bake without problem, but adding new 3d objects on top of the model doesn't seem to work. I have also sometimes added a few lowpoly models in 3dmax and then attaching those to the model for extra detail, but for some reason adding new 3d models/objects in zbrush greys out the normal map option. So my question is how I can easily add new 3d objects on the model and then bake them into the normal map.

So far I would import the model, subdivide without smooth, go back to level 1 and make a normal map test which works.

Then I make a new 3d model, make it into a new brush, to be able to draw I need to freeze my subdiv levels. Then I add in the new model ontop of the weapon, in an area where it would look good in the normal map. I unfreeze and first off both models now look awful, they start integrating and the topology gets destroyed, but even worse the normal map option is now greyed out. What am I doing wrong?

cryrid

Baking in Zbrush simply captures the difference between subdivision levels. It worked ok a decade ago if you were sculpting details via alpha brushes, but it's not so great if you are actually added new geometry.  If you add new geometry - even something minor like an inserted screw - then that geometry needs to exist on the base level and requires UVs in order to be able to create a map inside zbrush. And it's won't bake the way you want either (example:  the portion of the normal map for the body of the weapon won't show normals for the screw's details since that is a different piece of geometry with different UV coordinates). 

Use a program like Xnormal to bake. This will let you use different models for the two resolutions, so you can add whatever you want to the highpoly model. You'll also get a lot more control over the result as well (cages, custom vertex normals, specified tangent basis, etc) .