Right - quick background. I'm stuck at 2.79b because my laptop doesn't like 2.8/2.9 (and/or 2.8/2.9 don't like my laptop). I'm using Windows 10.

I'm baking images succesfully using Blender Render, but when I switch to Cycles Render the Bake throws an error and won't run.

My preparation was to run a physics sim to drop a bunch of pebbles into an invisible tray. So I now have a bunch of pebbles in an invisible tray.

My goal is to bake normal, AO, and displacement, maps of the pebbles to a plane (see first three images below, which are the result of doing this successfully with 'Blender Render' selected. Note: After I first found out how to do this sort of baking (9 years ago, 2.49b I think) I wrote a guide How To Model A Seamless Tiling Texture mainly so that I wouldn't forget how, and those are the instructions I followed this time. Successfully. Until I tried using Cycles.

It worked fine when I had 'Blender Render' selected:

However, after doing those I simply changed the renderer to Cycles, hit the Bake button, and got this:

Sure enough my baking plane didn't have any material assigned, so I fixed that thus:

I hit Bake again and got this:

I'm starting to go round in circles now and getting myself confused - I tried adding an image texture to the material, adding an image node into the material, got circular references, etc...

So can somebody cut to the chase and tell me what I need to do to get past this ?

Turns out to to be ridiculously easy, but not very intuitive (at least not to me - which is why I wrote that guide the first time I found out how to do it).

You apparently need to add an unconnected image texture node to the material, and then with that node selected open the render tab of the properties panel and hit Bake. It takes longer to render, and even with a UV/Image Editor panel open you don't see the image gradually appear as you did with Blender Render, but you see a progress bar at the top. The image appears once the bake is complete, or when you hit escape (obviously only a partially complete bake)

Here's where the penny started to drop... Need some help baking, “No active image found in material”

...and here's the ker-ching ! - Sweenist's third comment... Baking in Cycles - No Active image found in Material x for object y

Here's the Cycles Normal and AO (the rocks have a PrincipledBDSF material as per this Youtube video) - not sure what the extraneous bits at the edges are...

...but there's no diplacement Bake option ?

P.S. The reason I wanted to use Cycles was that I wanted to use a Cycles material and bake a Diffuse/Albedo/whatever-you-want-to-call-it map. But when I baked the Diffuse map this is what I got:

What I was expecting was rock type colours, more akin to the partial render below:

So what's up there then ?

Hello 3dcheapskate

Just curious have you heard of the TexTool it is an add-on for Blender it is free and is compatible with 2.79 and think it might help you in the future with much of what you showed above maybe you might want to take a look at it I have used it and even at most of its default settings I have found pretty useful it was orginally developed for 3Ds Max but the creator ported it for Blender

TexTools for Blender

No, I'd never heard of them. I've just read a bit about them and they do sound good, so I've installed them.

My biggest problem is that I'm a rather irregular Blender user, and I use probably far less than 1% of its capabilities. When something doesn't work as expected I don't really have a clue what to try or where to look.

Trying to do a simple tangent normals bake of my pebbles using TexTools isn't working as I'd expect...

The extraneous bits on the sides are probably due to the pixel margin. If you want to bake only colors or albedo without lights and shadows, be sure you're choosing "Textures" as the bake mode. I haven't used 2.79 in years, and I usually do baking with the Simple Bake addon. It's been quite a while since I used vanilla Blender baking features, but those are a couple of things I do recall.

I remember a tutorial that helped to understand baking a bit better it was done just at as Principle Shader was first being developed but maybe the info in these two might help granted one also involves using Substance Painter but part of the baking is done in Blender so can ignore that portion but maybe there is some general information that might help you in the future hope they help some

Introduction to Cycles Baking

How to create a grimy barrel scene in Blender and Substance Painter

LuxXeon posted at 12:53AM Sun, 21 February 2021 - #4412955

The extraneous bits on the sides are probably due to the pixel margin...

Thanks, the size of those extraneous bits does indeed correspond to the Margin setting on the bake (I confirmed by rebaking with it set to 8). Here's a close-up of the original Cycles AO bake with a 16 pixel margin for my own reference

LuxXeon posted at 12:53AM Sun, 21 February 2021 - #4412955

...If you want to bake only colors or albedo without lights and shadows, be sure you're choosing "Textures" as the bake mode. I haven't used 2.79 in years, and I usually do baking with the Simple Bake addon. It's been quite a while since I used vanilla Blender baking features, but those are a couple of things I do recall.

The 2.79b Cycles bake doesn't have a 'Textures' option, just 'Diffuse' (see screenshot at the end of this earlier post) - I'm assuming that using 'Diffiuse' as opposed to 'Combined' is correct ?

Lobo3433 posted at 1:26AM Sun, 21 February 2021 - #4413000

I remember a tutorial that helped to understand baking a bit better it was done just at as Principle Shader was first being developed but maybe the info in these two might help granted one also involves using Substance Painter but part of the baking is done in Blender so can ignore that portion but maybe there is some general information that might help you in the future hope they help some

Introduction to Cycles Baking

How to create a grimy barrel scene in Blender and Substance Painter

Thanks for the video links, I'll sit down and watch them both some time.

Those BlenderGuru videos are usually the first place I look when I have a problem, but he's done so many it's often difficult to find the relevant one.

I hope they help the grimy barrel one I did from start to finish and got a better understanding of where and how things need to be plugged into the Principled Shader and the differences between color and non-color data and how easy it is to miss not changing them and creating a headache for yourself

In accordance with the manual:

Diffuse, Glossy, Transmission

Bakes the diffuse, glossiness, or transmission pass of a material.

-- If only color is selected you get the pass color, which is a property of the surface and independent of sampling refinement.

-- If color is not selected, you get the direct and/or indirect contributions in gray-scale.

-- If color and either direct or indirect are selected, you get the direct and/or indirect contributions colored.

So, it seems if you are doing the diffuse bake, you need Color selected without direct or indirect, because your example appears to be baking the indirect contribution in grayscale?

Honestly, it's been so long since I used 2.79 I can't recall exactly the settings and I no longer have it installed on my machine unfortunately to check. However, that does seem to be the issue with your diffuse bake, in that it may not have "Color" selected? Make sure only Color is selected in the options settings of the Diffuse bake.

Since I actually do when I first did the How to create a grimy barrel scene in Blender and Substance Painter tutorial I ran around in circles trying to figure that one out I watched the tutorial maybe half dozen times before I saw the diffuse channel and changed it this doesn't come as much now but when Principle Shader was first introduced simple little setting like the color or non data were a big issue if you didn't already have it ingrained intuitively