Rendering Still Images in Owlet
When your scene is ready, it is time to render it. There is a button for that in the toolbar:
or you can start rendering by clicking Tools -> Render Scene menu item.
When you click the rendering button, the rendering settings window pops up:
The Width and Height input fields allow you to enter the resolution you are going to render to. The higher the resolution, the more it takes to render a nice image. Keeping this at “HD” level might be a good idea in most cases.
The next is Keep scene aspect ratio box that locks width to height and vice versa. This is good when you need, say a 16:9 rendering and don’t want to calculate the proper height by the width yourself. You can change the camera aspect in the camera settings panel. By unchecking this box you unlock width and height and can edit them independently. This way the camera aspect ratio will be changed for that rendering.
The next section controls the rendering time and quality. Owlet renders scene in many passes and each rendering pass adds to the previous ones, making a better picture and removing noise. It is you who decides when to stop. Imagine taking a photo in low light with small exposure time. You’ll get a noisy image, right? The same happens to Owlet - the longer you render, the less noisy image you get. The Rendering preset lets you choose the way you control the rendering time. There are basically two types of rendering time limitation: by the number of iterations and by time. The first method tells Owlet how many rendering passes to do and the second method tells how long should it render, regardless of the number of passes. Here are the presets Owlet provides:
- Draft - a fast and noisy rendering of just 100 iterations, which is usually enough to undertand if the scene is rendered right;
- Production - a preset for rendering of 2000 iterations - that is enough to render a nice image in most cases, except for the complex lighting scenarios;
- Iteration-based - this time you enter the number of iterations, it can be something between 1000 for simple scenes to 10000 or more for the complex ones;
- Time-based - by choosing this you will be askes to enter desired rendering time instead (in HH:MM format), Owlet will render scene for that exactly time and you get the most that can be done in that time.
The time-based method is much more predictable if you need to render a lot of images.
Advanced Parameters section lets you specify some extra parameters to render exactly the image you need:
- Brightness limit - limits the maximal brightness of the pixel. 1 means 100% white, but that’s not a limit. The recommended value is 4 for simple scenes without lights and 10-20 for scenes with bright lights and caustics. Sometimes you may even need to set this to 100 and more, but this may increase rendering time needed to reduce the noise;
- Render caustics - lets you choose between two rendering engines. The first one is simpler and somewhat faster, but it doesn’t take light effects into account. This mostly applies to caustics (focused light spots made by curve semi-transparent surfaces like glass or water) and sub-surface scattering. It is a good idea to keep this box unchecked unless you really need that extra light processing;
- Photon size scale - only affects caustics and should be 1 (100%) in most cases. However, sometimes you may want to adjust the size of photon spots and that’s where you can do this.
- Render extra channels - tells Owlet to render additional images for depth and normals buffers, and materials/objects colors texture (clown pass), it also enables the rendering of scene layers. These will be saved to extra images or (for PSD format) to extra layers. Consider saving to HDR format (PSD, EXR, HDR) to get the most of it.
Finally, there is a Render this job later box at the bottom that lets you queue the task for rendering it later. The queued jobs appear in job manager window.
When everything is configured you can click the Start button to start rendering.
In rendering mode Owlet shows the preview of the scene with the progress bar and the Good Enough button:
You can hover your mouse over the progress bar to see the rendering time and the estimation of how much time is left. The Good Enough button speaks for itself, if you feel that the image is already of a good quality, you don’t need to wait for the rendering to finish - just click that button to complete the rendering.
When the rendering is done, the results window pops up:
You can see the rendered image at the top and three buttons at the bottom:
- Save - lets you pick a file name and saves the rendering to one of the supported formats;
- Render More - re-runs the rendering process with the last used settings, so you can get a better image by rendering it again on top of the current image. This helps to reduce noise and improves image quality;
- Close - this button closes the window without saving results.