Day after day we have more and more great models to incorporate into our scenes. However, working with multiple assets makes our scenes increasingly heavy. Using proxies is a way to reduce filesize of scenes and this is a new feature recently introduced in Corona for Cinema 4D.
So today we launch our ‘how to’s’ section of our blog with corona proxies.
Firstly, we open the models we want to convert into Corona proxies. For this example we are going to use some models of cactuses by Maxtree from their collection nº17.
Then we create a new Corona proxy object from the Corona menu.
This will create an empty Corona proxy object: this means that this object doesn’t point to any geometry yet. Now, we can either pick an existing Corona proxy file or create a new one from any geometry present on the scene. In this example, we will create a new Corona proxy file by picking one of the assets present in our scene. To do so we just have to click on the “Pick from scene” button and then select the asset we want to convert into a Corona proxy file. Note that you can click just one object. If you want to combine more assets on a single proxy, you would have to group them on a null or placing one inside another. If you do so, in step 5 you would have to check on the “Include children” option.
We then save the new Corona proxy file on the desired location. This action will create a new Corona proxy file with the extension .cgeo in the choosen folder. Note that from now moving this Corona proxy file to another location would unlink all Corona proxy objects linking to it. To make it clear: it is the same as moving textures from one folder to another, you will have to relink them by telling Cinema 4D the new location of the referenced files. So try to save the Corona proxy file in the right location and try not to move them 😉
In the next window you can define if the geometry is animated or if you want to include children to your Corona proxy file. As in our example we only have a single object geometry with no animation nor children we just clicked on the OK button. The Corona proxy file has now been created and our Corona proxy object is linked to it.
The Corona proxy object works, but it has no materials. The easiest and fastest way is to copy the texture tags from the original geometry (still present on our scene) to the Corona proxy object. In our example, the exported geometry has different textures applied to different geometry selections, so be careful and check that your texture tags keep the correct names to their respective selection tags, as the Corona proxy files keep the selection tags set internally.
Then we rename the Corona proxy object to easily recognize it. Finally, our proxy is ready to work!
If you check on the Corona proxy object attributes menu, you will see there are a few complementary options right under the Corona proxy file location. The most important for us now is the Visualisation method, that can be switched from the default Wire bounding box to Solid bouding box, Point Cloud or Full mesh. We will choose Point Cloud visualization as it is lighter than the others. You can also choose how many points you want to display. 0% would mean 1 point, which is very light if you have to place many proxies in the scene. For this example we will keep the default 10% value.
We repeat the whole process for the rest of assets loaded into the scene. At the end we will have 5 geometry objects and 5 Corona proxy objects linked to 5 Corona proxy files that have been generated and saved in the desired folder of our model library. If you have created the proxies inside your working scene then you could now delete the original models and just keep the proxies, as they are lighter than the originals, and so will be your scene.
Finally, you can replicate them by hundreds with mograph or any other population tool you may be using. We are now able to render the image and enjoy the result 
To sum up, we want to notice that our example scene, with 25 cacti proxies has a size of 100MB, while the one with 25 models of cactuses is more than 1 GB. Corona proxies really make the difference optimizing scene file size!
Nevertheless there’s still a big drawback when using corona proxies in cinema 4d being that the visor of Cinema 4D becomes very slow while working with proxies using any display modes of the proxies. We actually don’t know if it’s a Corona performance issue or a problem native of Cinema 4D which is not yet able to handle the proxies. We hope that Corona or Maxon developers work together to solve this inconvenience soon!
