Computer graphics Labs: Blender (1bis/3) SketchUp model importation and animation

Transcription

1 Computer graphics Labs: Blender (1bis/3) SketchUp model importation and animation University of Liège Department of Aerospace and Mechanical engineering Designed with Blender 2.76b and SketchUp 8

2 From SketchUp to Blender SketchUp model prerequisite (optional) Before exporting a SketchUp model, two things need to be checked: Firstly, importing SketchUp components into Blender is not possible at the moment. Therefore components included in the SketchUp model should be burst before exporting. To be sure there are no more components in the scene, select all objects [ctrl-a] and make sure the burst option is not available anymore in the context menu (right click). If it is not the case, burst the model as many times as possible. Secondly, because faces are duplicated when exporting, it is needed, whenever possible, to make sure the same colour (or texture) is applied to both faces. Alternatively, do not apply any colour on the non visible face where the default colour should be kept. Exporting the model (optional) The SketchUp model is then exported to (File->Export->3D Model ) in COLLADA format and converted to the Autodesk 3DS Max format. A.3ds file is then created and possibly accompanied by a folder named the same. This folder contains the textures that were used in the SketchUp model. It is crucial to keep it with the file for Blender to be able to import these textures. The export result is gathered the archive folder piece.zip (available on the class web page) that include the file piece.3ds. Importing the model For importing the 3DS model into Blender: 1. Unzip the archive piece.zip into your working folder. 2. Launch Blender and erase [x] the default cube. 3. In the File Menu, choose: Import->3D Studio (.3ds). 4. Then navigate up to the file piece.3ds, select it and click on Import 3DS. Adaptating the model for a Blender Render Scaling Importing into Blender a model created in SketchUp sometimes generates a model whose dimensions are illsuited to Blender. This normally does not occur with the file piece.dar. Yet, if the object dimensions grandly exceed the camera lens, it is better to scale it in order to prevent further problems. 1. The Outliner allows the display of all the objects contained in the file. The resulting situation is presented in the adjacent illustration. The Outliner allows the rapid identification of the objects that have been imported from the SketchUp model. 2. To carry out a multiple selection in the Outliner, 2

3 click right on the object you want to be added to the selection and choose select. This way you can select all objects whose names are beginning with SkecthUp. 3. Then move the mouse cursor in the 3D window. Click [s] to activate the scaling mode and click 1.2 (the scaling factor) and then click [Enter] to validate. Adding camera and lamps 1. Switch to the wire mode by clicking [z] and switch to orthogonal projection by clicking [5]. 2. Move the default camera and the lamp; add an additional lamp to get the following situation: Top view Front view 3. Activate Ray Shadow for the lamp you just have created to cast shadows. This option is available in the tab Shadow from the panel Object Data in the Properties window. 4. Select the camera and switch to the panel Object Data of your camera. o To have a bigger part of the scene visible in the render, adjust the parameter Focal Length in the tab Lens. 5. If you want to launch a render now, you will see a result of bad quality and noised. This is caused by the duplicated SketchUp-imported faces that are disturbing Blender shadows render calculations. 3

4 Erasing Face Duplications Face duplications are caused by SketchUp creating, for all surfaces, a front and a rear face. This allows SketchUp to apply a different material on each face of the surface. Two cases are possible: Either the material is applied on both faces. In this case, vertices can be deleted from either faces ( Remove Double ). Or it was not possible to apply the same material on both faces. It is thus needed to select the material and to erase vertices corresponding to default SketchUp materials. Identical Materials In the SketchUp model provided for this session, so is it with walls, floor and ceiling. In order to delete superfluous vertices from these objects, follow these steps: 1. Select the object and switch in Edit Mode [Tab]. 2. Select all vertices [a]. 3. Click on Remove Doubles under Remove from the left panel in the view window. 4. In order to correct the normals, in the tab Shading/UVs click Recalculate under Normals. Follow these four steps for each object: floor, ceiling and walls. Different Materials Contrary to the walls, the faces of both cubes in the room are doubled and are covered with a different material on each face. It is the case when one of the faces was unreachable when modelling under SketchUp. Knowing that the default (white) material is then applied on internal vertices of the object, we will be able to select these vertices using their material to erase these same vertices. 1. Select the object. 2. Switch to Edit Mode and then make sure no mesh element is selected. 3. In the tab Materials of the Properties window, you may see that the object is linked to two materials. Select the white material in this tab. 4. Click on Select in order to select vertices related to the white material. 5. Move again the mouse cursor in the 3D window and delete [x] the selected vertices. Upon completion of these steps for both cubes, the render may be recalculated. It then should not be noised anymore. 4

5 Animation Creation Basic Camera Animation We will now begin to create an animation, in which the camera will rotate on a vertical axis. To this aim, we use the Graph Editor that is located in the Window Type menu on the extreme left header of each window. This window allows visualizing the parameters evolution of an object (position ) over time (time is represented by an image number). The curve editor functions the same way as the 3D window: Right clicking allows selecting a curve s control dots. Clicking and using the mouse wheel allows moving. [ctrl+click mouse wheel] allows zooming. [Home] adjust the window to all curves. [g] allows moving the selected entity. [ctrl+left click] allows adding dots to the curve. For creating the animation: 1. Add a window (or take an existing window) and select Graph Editor as a type. 2. Then select the camera and put it in its wished start position (in the direction of the lamp that is situated to its left for example). 3. Then click [i] and select Rotation in the popping menu. The result is the adding of three curves to the rotation of the camera. 4. Then switch to image #100 by using the box indicating the current image in the Timeline header window at the bottom of the screen. 5. Put the camera in its end position, for instance, with a 90 angle to right from the start position in order to sweep the whole room. 6. Click again [i] and select Rotation to insert a new dot in the curves editor. The evolution curve of the rotation angle is automatically interpolated (by a default Bézier curve). 7. It is now only left to define images for the start and the end of the animation. Get back to the Timeline window header and insert the index of the first (1) and last (100) image respectively in the Start and End boxes. 8. That animation can now be tested by clicking [alt-a] or by using control buttons from the Timeline header window. 9. In order for the render not to be too long, set the output at 25% in the tab Dimensions from the Render panel. 10. Before launching the render, select the output format of the animation in the tab Output in the Render panel from the Properties window. By default, the animation is saved as a series of images. To get a video from it, AVI JPEG is to be trusted most of the time. o The file is put in the directory specified under the tab title. Each format change needs a render to be effective. 11. Finally, click Animation under the tab Render located up the panel with the same name or use the shortcut [Ctrl-F12]. 5

6 Trajectory Follow-Up Blender also allows defining an object trajectory (such as the camera) using a curve (for example, a Bézier curve) directly defined in the 3D window. Creating the trajectory 1. Select in the top view and insert a Bézier curve (Object Tool panel->curve->bezier). 2. Switch to the Edit Mode and modify the obtained curve. It is allowed to add dots to the curve by selecting one of its endpoints, then, while clicking [Ctrl], click left on the location you want. 3. Exit the Edit Mode and put the curve on the desired level; add then a new camera (Object Tools panel->other->camera). 4. In order for the camera to follow the path we have just created, we will add a constraint. o Select the camera and activate the Object Constraint panel Properties window. from the o Click on Add Constraint and select Follow Path in the column Relationship. o A new tab related to the constraint appears. In the field Target, select the Bézier curve. o Click the box Follow Curve for the camera orientation to follow the curve. o The tab Forward informs of the camera axis that will remain tangent to the curve (and oriented in the same direction as the latter). Select X or -X for the camera to remain perpendicular to the curve or -Z for the camera to be tangent to the curve. o Finally, the Up tab informs of the camera axis that will be oriented upwards. Select Y. If at this stage the camera is not located on the curve, switch to the visualization window and activate the Properties panel [n]. Then, select the camera and define its coordinates as 0 (position and rotation). 5. Likewise, it is now needed to define the position of the camera (on the curve) for at least two images (key-images). o Select the curve and activate the panel Object Data. o Switch to the tab Path Animation. The Frame box value is, by default, set at 100. This box value represents the length of the curve. You may leave the default value. 6

7 o The field Evaluation Time informs of the camera s current position on the curve. This field value may vary between 0 (curve start) and the Frame field value (curve end). Set yourself at image 1 and set Evaluation Time at 0. With the mouse cursor on the box Evaluation Time, click [i] to introduce the first key-image. Then, set yourself at image 100 and set Evaluation Time at 100 to set the camera at the end of the curve. Click again [i] on the Evaluation Time field in order to insert a second key-image. 6. A curve has been added to the window Graph Editor. Only curves related to the object selected in the 3D window are visible in this window. o The default interpolation between key-images is a Bézier curve. In order to get a linear interpolation, click [a] (sometimes you need to click twice) in order to select all dots on the curve; then, in the menu Key ( Graph Editor window header), choose Interpolation Mode->Linear. 7. Finally, in order to make the camera active, get back to the 3D visualization window and select the camera. In the visualization window header, choose View->Cameras->Set Active Object as Camera. o The animation can then be tested by switching to the Camera View [0] and by clicking [alt-a] o It is also possible to tilt the camera downwards while modifying the Rotation value according to X in the tab Transform in the Properties panel from the Visualization window [n]. o If the result is satisfactory, then calculate the render [Ctrl-F12]. 7