**UPDATE:** As of Version 2.79 Cycles (currently avaliable as a [testbuild](https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.79)) there is an option to make an object a shadow catcher. [![enter image description here][1]][1] [![enter image description here][4]][4] From the [release notes](https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.79/Cycles) >This option will make object to only receive shadows in a way that it could be alpha-overed onto another image. Enable Film: Transparent. [![enter image description here][2]][2] (qoute from the [develpoer's notes](https://developer.blender.org/rBd14e396)) >The workflow is following: >Create an object which matches real-life object on which shadow is to be catched. >Create approximate similar material on that object. >This is needed to make indirect light properly affecting CG objects in the scene. >Mark object as Shadow Catcher in the Object properties. Ideally, after doing that it will be possible to render the image and simply alpha-over it on top of real footage. Once the plane has been marked as a shadow catcher, just render! Again from the [release notes](https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.79/Cycles) >It is to be noted that shadow catcher objects will interact with other CG objects via indirect light interaction. For example, shadow catcher will be reflected in the glossy surfaces. [![enter image description here][3]][3] **OLDER ANSWER:** You can do a shadow catcher using a shadow pass and different render layers to create an alpha channel for the scene: [![enter image description here][5]][5] - Move the plane object (shadow catcher) to layer2. - Make a copy of the other objects and move them to layer 2. The idea is that on layer 1 you only have your objects but not the plan, and on layer 2 a copy of your objects and the plane that will act as shadow catcher. [![enter image description here][6]][6] - On all of the objects in layer 2, except for the shadow catcher plane, disable Ray visibility for camera. You want the plane to be visible, but the other objects should be transparent to camera and projecting shadows on the plane: [![enter image description here][7]][7] - Make sure your lamps and camera are active in layers 1 and 2. [![enter image description here][8]][8] - Set up two render layers: One for the objects in layer 1 that excludes information from layer 2. A second render layer for the shadows that includes a shadow pass and excludes layer 1. [![enter image description here][9]][9] - Enable Transparent on the Film section. [![enter image description here][2]][2] - In the compositor you can use the shadow pass to alter the values of the alpha channel of the object's layer. Add an invert node to shadow pass and plug the result as factor on a mix node (in add mode). Plug the alpha channel of the object's layer to the top socket and leave the lower socket empty. [![enter image description here][10]][10] You can control the transparency of the shadows by changing the color on the empty socket of the mix node. If you make that color white the shadows will be fully opaque, if you make it black you'll have no shadows. Alternatively you can use the values from the shadows layer and the transparency of the shadows will be set using the values from the original scene: [![enter image description here][11]][11] For softer shadows you can add some blur: [![enter image description here][12]][12] [<img src="https://blend-exchange.giantcowfilms.com/embedImage.png?bid=1072" />](https://blend-exchange.giantcowfilms.com/b/1072/) [1]: https://i.sstatic.net/7CkYi.png [2]: https://i.sstatic.net/ga8zt.png [3]: https://i.sstatic.net/1PLRY.png [4]: https://i.sstatic.net/GZRI6.png [5]: https://i.sstatic.net/Kk9fh.png [6]: https://i.sstatic.net/QE6BG.png [7]: https://i.sstatic.net/XP39S.png [8]: https://i.sstatic.net/8hSPi.png [9]: https://i.sstatic.net/Prugx.png [10]: https://i.sstatic.net/dP3rp.png [11]: https://i.sstatic.net/TJcZG.png [12]: https://i.sstatic.net/XV6VQ.png