THEA RENDER WALKTHROUGH ANIMATION

Transcription

1 THEA RENDER WALKTHROUGH ANIMATION INTRODUCTION Walkthrough animation is a special kind of animation, where the only thing moving in the scene is the camera. You can see an example of a walkthrough animation at the Thea Edition 1.2 Tutorials page (a preview of this animation is also seen in Figure 1). At this tutorial we will see the way we can prepare such an animation for rendering, by giving the main steps to set up the animation and make the needed adjustments for faster and smoother results. Along with this document you are welcome to download the corresponding scene to see the camera and engine settings. Figure 1: Walkthrough Animation SET UP A WALKTHROUGH ANIMATION The first thing that one needs to do for creating a walkthrough animation is to make a camera move around the scene and create its motion. Like all other animated objects, motion to a camera is applied by the following steps: 1. Open the Animation Toolbar (see Figure 2) for setting up the key frames of the animation. 2. Move the selected camera at the point the animation will start and set up a key frame at the corresponding frame (zero for example). For adding a key frame you need to use the white key button as seen in Figure Go then to a different frame by dragging the frames bar. Move your camera to another point of the scene, adjust its view accordingly and set up a new key frame. 4. Follow the previous steps as many times as needed for creating the animation of the camera. You can see the path of the camera with a blue line and with green dots the key frames that you have set up (see Figure 3). 5. You can go to the selected camera view and play the animation to see the way the camera moves around your scene and make any needed adjustments. Figure 2: Animation Toolbar Version used for this Tutorial: Presto Edition v Build 916

2 Figure 3: Camera Animation at our case study scene Blue line shows camera motion and green dots represent the defined key frames Tip: in order to get a smooth and nice animation, try to use an appropriate speed for the camera movement. Camera speed affects both the render settings that we will make (as explained later) but also how good our animation will look like. Very fast camera movement could be unrealistic. By using a frame rate of 25 for example, means that each second of our animation will be shown by 25 frames. Within this second, if we have made the camera move for example along a 10 meters distance in 25 frames, our animation would be too speedy. Slower camera motion may require more frames but the final result will be much smoother and natural. MAKE ADDITIONAL SETTINGS After creating the camera motion, we need to make some additional adjustments at the Animation settings panel in the way we do for any other animation. At the Frames panel, as we see it in Figure 4, we can specify the total animation frames, the frame rate and which frames will be rendered (all, current one or selected frames). Here one can write either frames numbers separated by comma or by dash or a combination of these. For example we can type: 3, 4-8, 12. The frames that will be finally rendered will be the 3, 4, 5, 6, 7, 8 and 12. We can also select the Frame per Bucket Pixel option for network cooperation. Figure 4: Animation Settings Panel The most important panel here (for our case) is the Walkthrough panel. At this panel, as its name reveals, the settings for the walkthrough animation exist. Note that these settings are used for the Adaptive (BSD) engine only. If the scene is set up as described above (you have used a camera to move around your scene and no other movement exists) and you have used the Adaptive (BSD) engine, you can enable the walkthrough animation option of this panel for making render times faster and final animation smoother. 2

3 PREPASS LEVEL Prepass Level: from this drop-down list (see Figure 5) you can specify the desired Prepass Level for the walkthrough animation, meaning the irradiance computation per frame. More precisely, the prepass level in the animation panel will "average" or "smooth" the differences in Global Illumination (GI) calculation between frames. Figure 5: Prepass Level Values With the prepass level enabled, Thea will average the frames Global Illumination and with this way if any artifacts exist in the scene, they will not flicker at the produced animation. Concerning the values that we see at the drop-down list, 1/1 is the default one, above it we see higher values and below it we have the smaller ones. Let s say that we use as a prepass value the 4/1. In this case Thea will use frames 0, 1, 2 and 3 to average their GI to produce frame 0. The next step will be to take frame 1, 2, 3 and 4 to average GI and produce frame 1 and so on, until producing all frames. With this procedure the final rendered frames will be very consistent between each other (but the prepass level calculation times can be much bigger). Normally with a prepass level value at 1/1 we can have very smooth final results and small prepass calculation times. For increasing or decreasing the prepass level value we need to take under consideration the following parameters: - The Global Illumination settings (the parameters we have used for setting up the Adaptive (BSD) engine). The higher the accuracy of the settings we see at the Global Illumination panel, the fewer artifacts will be produced and the prepass level value of the walkthrough animation can get lower values. If though, for making render times smaller, we have used for example fewer samples or lower density etc., we will need to increase the animation prepass level value to avoid flickering between frames or artifacts like black areas at some frames. - The speed of our animated camera (which is a very important parameter). If we have a good GI solution and the camera moves relative slow, then we can even use a prepass level of 1/5 or even lower. This is possible because there are no abrupt changes between frames and Thea can calculate the missing samples easily. But if the camera moves very fast, there will be many changes between frames and we cannot afford to exclude any frame from the prepass calculation, because this will cause flickering problems at the rendered animation. In this case we need to use at least a prepass level 1/1 (or Figure 6: GI Settings Panel higher). 3

4 At the next images we can see the way some animation frames look like for different prepass level values. At the first set of images that follows we see a single frame rendered with prepass level 1/1 and then the same frame rendered with prepass level 4/1. In both cases we have used the exact same Global Illumination settings, and we see that the frame rendered with prepass 4/1 is smoother and better then the frame rendered with pre pass 1/1 (differences are not easily seen by first observation, but can be seen by a closer look). Figure 7: a single frame rendered with prepass Figure 8: the same frame rendered with prepass level 1/1 level 4/1 At the next set of images we see 2 frames showing the artifacts that can occur when we use a too low prepass level like 1/5 or 1/10 with a very fast camera movement. As we have said, using a pre pass level 1/1 is good for most walkthrough animations and depending on the speed of the camera movement we may use higher prepass levels or lower, if the camera moves very slowly. Figure 9: frame rendered with prepass level 1/5 Figure 10: frame rendered with a prepass while camera moves very fast level 1/10 with a very fast camera movement 4

5 After making these necessary settings we can go at the Darkroom and start rendering the frames sequence that will produce our animation. Note that when the walkthrough animation option is enabled, Thea will calculate at first the whole irradiance pass of all the animation frames and after that it will ray trace the frames one by one. Please keep in mind that even if the irradiance computation for one frame can take quite much time (10 minutes for example) this is not an issue for the walkthrough animation, as at the next frame, only some samples will be added to the irradiance calculation and so, in the end the total irradiance cache calculation will not take as much time as the ray tracing actually takes. This means that as each frame needs to get fully ray traced, for reducing the total render times we need to focus more on ray tracing settings rather than decreasing the Global illumination settings and/or prepass level values. 5