Baking projected photos onto object texture

Hi all,

I’m completely new to Blender as of yesterday, so apologies if any of this is stupid/obvious.

I am trying to get some clay models converted into 3d models for use in a game. I have used 123D Catch to capture the object’s geometry and texture, but the output is not suitable for game use in its raw form… and so, I turn to Blender.

I’ve followed some tutorials on retopologising, and have managed to build a nice, tidy low poly mesh that follows the geometry of the scanned object. So far, so good! Now, all I have to do is get the photo textures onto the object and I’m all set to go. Unfortunately, it’s at this point that I’ve found myself a bit befuddled.

I seamed and unwrapped the object to create a UV map on a texture page. Great! Now, I just have to somehow get the textures from the photos baked onto my object’s texture. It would be nice if I could somehow just project them straight on from the high-poly model, but if that isn’t possible it would be fine if I could open up some of the source photographs, align them with the object, and project them onto the texture that way. I had a look at some UV Projection tutorials, but, like I say… I’m befuddled.

Ideally I guess I want to load up a photo, have it displayed on screen, line up the model so it matches the angle of the photo (which won’t be orthographic or necessarily straight on), and then bake that projection onto my texture. If I have to do it in several passes and combine multiple textures together in Photoshop, that would be fine (providing each pass bakes the texture onto the same UV map).

I kind of feel like… it should be possible, and maybe I’m nearly there, but I can’t quite put the pieces together. I can’t figure out an easy way to line up the photograph with the model, and I don’t know how to get Blender to bake the texture onto the other texture.

Any help would be most gratefully received! As I say, I’m totally new to Blender so I’m not always completely sure where the various buttons, menus and options are hiding… especially since the UI has changed a lot since most of the tutorials were made.

It’s certainly possible to eyeball and place object in 3dview like in photo, UV unwrap Project from view and use that same photo in uv editor window to use it as a texture for object. That will be textured object from one side. The rest of it will be mess. If you don’t need back side you’re done.
So, you need additional reference photos to project on other sides of object.

In essence - you have one full uv unwrap and designated texture file for object and then make necessary temporary uv unwraps from different source images adjusting objects position before this temp unwrap, which could be combined using, say, texture paint clone.

As to the buttons to push - that’s a long story and you’re better off watching some videos on subject.
I used to refer to an old 2.4x series video on Vimeo - Unwrap and texture stone tutorial, but while idea is the same, buttons are in different places mostly, which will cause confusion…

Projection painting is indeed the way to go if you have many photo references from every side. Very usefull feature i used it a lot in 2.49b

Here’s a tutorial for 2.5 (works the same as in 2.6) about it :

Fantastic, that tutorial has made everything clear. First model now successfully textured! Project is back on track - thanks people.

I’m quite sure you could “bake” the textures from your high res model to your low res retopo model.

In the uv editor for the low res model, make sure you create a new image texture, and set up the uv coordinates correctly.

Make sure both your high and low res models are on the same layer. Select the high res model, then shift-“right click” to select the low res model aswell. Make sure you select the low res model LAST though, so it is the ACTIVE selection.

Then in the render tab, scroll down to find the subsection called “Bake”.

In the “bake mode” dropdown menu, select “textures” and check the option “selected to active”. Then press the big “Bake” button. The ui will stop for a moment. If you have the uv editor in a window, you’ll see the window fill with an image, and once the bake is finished, the uv editor will be filled with the image, and then save that image to your hard drive, and use it as the texture for your low res model.

That would be brilliant, but whenever I try it I get “no objects of images found to bake to” error. I’m flummoxed by this as I DO have a texture with UVs unwrapped on it from the low poly model. When I select the low poly model and go into edit mode and select all, I can see it there in the UV map window with the UVs all mapped correctly.

Check the following to see if you have not forgotten a step , for me it has worked every single time i tried to bake something from a high poly to a low poly version of the same model.

  • Have both high poly and low poly version at the same location, be sure to select them and to make sure there will not be problem during the baking press CTRL+A -> Apply Rotation/Scale for each of them (or Object -> Apply -> Apply Rotation/Scale).

  • In Edit ModeHave the low poly to be unwrapped, and have a texture assigned to it in the UV/Image editor, even if it’s a texture that is using 1 color or if you’re using the test grid, it’s not important, the low poly needs to have both an UV and 1 texture assigned to it.
    The only time i had a “no objects or images found to bake to” message was when i forgot to assign 1 texture to the low poly model in the UV/Image Editor.

  • In Object Mode, select the high poly model, press SHIFT then select the low poly model, in that order.

  • In the Bake tab , make sure “Selected to Active”" is enabled and select the bake type you want (“Texture” in this case), then press Bake.

Hmm, nope. I reverted to an earlier save, just in case my adventures with multiple UV projection had messed things up.

They’re both in the same place, although the retopo-ed object is semi-intersecting the high-poly model. Is there something else I have to check on the texture to have it assigned? It’s definitely texturing the low-poly object (it displays the test grid, currently - and if I pull out the texture paint brush I can paint onto the object/texture), and when I select the object in edit mode the UVs show up on the image. But when I click bake, the texture image disappears from the UV window, the grey grid appears in its place, and the error is thrown.

I feel like I’ve neglected to click something somewhere, or at some point maybe clicked something I shouldn’t, but I’ve checked everything that’s been mentioned. Is it maybe because the meshes are semi-intersecting?