360 Images with Corona

Corona Render is a rendering engine for 3ds Max that can render 360 images. It is a simpler and cheaper alternative to Vray for 3ds Max. It also uses the computer's processor to render, so there is no need for a special graphic card.

Below are the required steps to render 360 images using Corona.

Make sure you have Corona installed for 3ds Max. You can start with a free 45 day demo.

Link your Revit file

In Revit, save your file. Then, open a blank file in 3ds Max. Save it immediately into the same directory with an appropriate name.

After this is done, you can link your Revit project. In 3ds Max, click the "3" at the top left and select "Reference", then "Manage Link". Select your original Revit file, then select a camera View and click OK. The default preset "Autodesk Revit - Combine by Revit Materials" should be selected. Click "Attach this file". Once the file is loaded, close the "Manage Links" window.

Note: Some scaling issues can arise if your Revit units are not set to feet.

Convert to Corona

At this point, your scene should be imported in 3ds Max. We will need to convert everything so that Corona can render it properly. In the top menu, click "Scripting", then "Run Script...". Open the "CoronaRenderer" folder and select the "CoronaConverter" script.

Make sure the converter has "All" under the conversion settings and click "START CONVERSION".

You will see a warning that "Autodesk Materials" are likely not well converted. While we generally recommend avoiding Revit Autodesk Materials  (except Generic Autodesk Materials), you can fix these by lowering their materials' glossiness factor in 3ds Max's Material Editor.

Your file has now been converted and you are almost ready for rendering.

Turning on the Lights?

Note: If you want to render with just the sun on, skip to the "Apply CoronaCameraMod Modifier" section.

If your Revit model used electrical light sources, you can turn these on in 3ds Max. By default, artificial light sources come in "off" when you import your Revit file. By default, the sun is on, so you could leave the artificial lights off, if there is enough sunlight in the rooms you are trying to render.

Keep in mind that every light that is turned on will make your render slower. As a rough rule, a scene with 100 lights will render 100 times slower than the same scene with one light (the sun). It is also useless to turn lights on that will have no effect on your scene. For example: turn off the garage lights if you are rendering a room on the third floor. This will speed up your render time.

To turn on the lights, click "Tools" in the top menu and then "Light Lister". For every light in the Light Lister's Photometric Lights, toggle the "On" box. You can now close the Light Lister tool.

You will most likely need to fix the geometry of most of the lights, since 3ds Max doesn't seem to import this Revit data properly. To apply the proper luminous shape, you must know what the original shapes and sizes were in Revit or what makes sense considering the light fixture and lamp shape. Select each light type and adjust the shape and sizes appropriately.

For example, this spotlight is specified as a 2' by 0'0 1/32" rectangle. This is obviously wrong so we will change this value to be a 6" diameter disk (3" radius). We can verify the results visually by looking at the light fixture and the associated light emitting shape.

This can also be done directly within the Light Lister Menu, but it is harder to verify if it worked properly without examining the resulting light geometry. Thankfully, this adjustment only has to be done once per light fixture type.

If you are not comfortable applying the proper shapes to the luminous area, we suggest leaving the artificial lights off or waiting for Autodesk to fix this standard workflow. In a room with a lot of sunlight, turning on the artificial lights will often not make any difference. Since the sun is so much more powerful than artificial lights, it will only make your renders take longer. You can get more dramatic effects if you turn off the sun or set the time to a sunrise or a sunset.

Apply CoronaCameraMod Modifier

In the next step, we will transform a regular camera into a 360 camera.

Select the camera you would like to render and add the "CoronaCameraMod" modifier in the Modify Tab.

Enable Projection Type. It should be set to spherical.

Enable Spherical Mod. Set the eye separation to 70mm or 2.75". This is the eye distance that is built into the GearVR.

Render the 360 Image

Press "C" on your keyboard to bring up the camera menu. If your scene has multiple cameras, select the camera you just modified. You should be seeing what the camera sees, but not as a 360 image.

Open the "Rendered Frame Window", then "Render Setup".

Make sure your rendering engine is set to Corona. 

Set the Output size to 4096 x 4096 pixels or another smaller resolution with a resolution of 1:1. Pixel aspect should be set to 1.

You can set a render output and select a directory and file name if you want your image to be saved automatically once the render is done.

In the Scene tab, place a time limit if you want the render to go on for a specific amount of time. The renders settings from Corona don't need to be modified, you can keep the default settings.

Press "Render" when you are ready. If you have multiple windows opened in 3ds Max, make sure your active window is your camera window or else the wrong window will be rendered.

Edit and Save File

Corona is great because it lets you edit the exposure value during and after your render. The render starts out blurry and gets less blurry over time, this will allow you to see material, lighting or camera errors right away. Play with your exposure and highlight compression settings until you are happy with the image. The Highlight Compression will add details to overexposed areas. To adjust the setting, hold your mouse over the arrow buttons and drag up and down.

If you are satisfied with the image, you can press "Save" and save it as a JPG file while it is still rendering. You can also wait much longer until the image is crisp and clear.

Upload to InsiteVR

Once you've saved the JPG file, you can upload it to InsiteVR and share your renderings on a regular screen, a cellphone or embed them into your 3D model walkthrough for VR.

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