The backdrop image will not appear in compositing. I had the same problem in another tutorial. The image does show up on the Render Layers node, but that's as far as it goes. Ctrl+Shft+click was supposed to create a viewer node, but that didn't work either. I have v2.76.

There could be a number of things that are going wrong with your node setup and render layer setup.
I will make some assumptions here:

• You have your scene elements organised on appropriate layers matching your render layer set up.
• Under the "Render" tab you have "Transparent" checked in the "Film" section for the scene elements that you want to composite.
• In the attached picture you have the highlighted areas under the "Check" text selected in the Node Editor.
• The "Backdrop" image you mentioned is a separate image.

The attached image shows a basic node setup to composite an "object" render layer with a "shadow" render layer on a separate background image.
To add your viewer node press "Shift+A" and select it from the Output options.

Thank you, Keppel. This is a pretty basic project compared to that. I think Transparent takes out the World: Sky background. Here's the current tutorial I'm working with (Magic Mineral): https://www.youtube.com/watch?v=KpWWYEF59lo The part I'm stuck on begins at about 46:40. It's one of the best tutorials I've seen, showing each step and even explaining why he's doing it. I've learned more about how the nodes work from this than any other.

Here's another with the same problem (Simple Energy Effect): https://www.youtube.com/watch?v=bnrsoSagIU8 Trouble at 9:30.

Since both projects are having the same problem, I'm guessing there's just a detail I'm missing that was too obvious for them to mention. They both use older versions of Blender, 2.66.1 and 2.7. Comments mentioned some node issues with newer versions. Thank you for your help!

I've looked at the videos you linked to and I now have a clearer idea of what you meant in your original question. The backdrop image you are referring to, that shows in the compositor behind the node setup, is a result of the connection of the viewer node. If you have a viewer node connected but the backdrop checkbox unchecked then there will be nothing displayed. If you have the backdrop box checked but no viewer node then again nothing will be displayed. If there is no completed render result to feed an image to the render layer then again nothing will be displayed.

I am using Blender version 2.77a and can't replicate the problem you are describing in so far as no backdrop image appearing with the proper node setup but I can offer a couple of suggestions.

• In the Energy Effect tutorial it looks like the author clicks on the render layer node which resulted in the image appearing (it was subtle and I may be imagining it).
• If still nothing happens try re-rendering once the node setup is connected.

The Ctrl+Shift+Click you are referring to is a feature of the Node Wrangler addon which comes with Blender by default so make sure that this is activated in the User Preferences>Addons. To make it work press and hold Ctrl+Shift and then Click on the node that you want the viewer node to connect with. If you just click anywhere nothing will happen. In the Magic Mineral tutorial creating the viewer node connection with the Ctrl+Shift+Click method requires the render layer to be clicked on (like with the Energy Effect tutorial) resulting in the backdrop appearing.

Thank you!! Haven't gone back to the Energy project yet, but this seems to be working for the Mineral.

Is there a particular purpose for using the Backdrop instead of just having the image on one side and the nodes on the other?

Personal preference and maybe saving some screen space by combining two functions in the one area. If you do want to have the nodes in one workspace and the image in another then consider having the image workspace set to UV/Image Editor instead of the Node Editor. That way you don't need a viewer node as the composite node is what sends the render result to the UV/Image Editor, and your node tree won't obstruct your view of the image.

Thank you Keppel!