Sculpting a 3D landscape (Maya) How to create a 3D interactive character moving inside a rendered image of a landscape (Virtools) JMG Spring 2008

Transcription

1 Sculpting a 3D landscape (Maya) How to create a 3D interactive character moving inside a rendered image of a landscape (Virtools) JMG Spring 2008 This tutorial has two parts. Part 1- Sculpting a 3D landscape (Maya) and part 2- how to create a 3D interactive character moving inside a high resolution 2D rendering of a the scene. The character can navigate inside a high resolution picture that would be difficult to process in real time. Left illustration, a 3D interactive character walks inside a high resolution rendering. Right illustration, the meshes used for the ground and for the obstacles are hidden during playback. The camera viewpoint in Virtools is the same than for the scene created in Maya. Cameras, lighting, meshes for grounds and obstacles from the Maya scene are exported to Virtools. Fluids or paint effects are rendered using Mental Ray in Maya. The rendered image is imported in Virtools as a 2D frame. Although 3D objects and meshes of the scene are made invisible, they create believable interactions between the character and the 3D scene. They keep their collision attributes as floor and obstacles. The character can also project realistic shadows on the details of the ground. View of the final setup in Virtools, character walking inside a high resolution rendering. Part 1- Sculpting a 3D landscape (Maya)

2 In Maya, create the ground. Go to Create > Polygons primitives > Plane, subdivisions Please note that a low polygons ground will be easier to model. Let s use Paint Effects. I suggest selecting the ground plane, as an object (green selection) > go to Paint Effects > Make Paintable. You can now snap the Paint Effects brush strokes on the ground plane. TIP: Drawing a simple X shape with Paint Effects and placing a camera between the lines of the X creates a great landscape with foreground, middle ground and background. For example, draw using the Clouds> Smoke brushes. Windows > General Editor > Visor > Clouds > SmokeRisingDark. Go to the attribute Editor > select the strokeshapesmokerisingdark tab, Display Quality = 200. And select the SmokeRisingDark tab, Global Scale = Use Windows > Outliner, in order to select each brush strokes of the Paint Effects. If you model the plane after applying the Paint Effects, the Paint Effects will follow the transformations of the ground plane.

3 TIP: You can add brush strokes on a new layer. Create a new Layer > Turn the layer into a visible template (V and T). The layer is visible but objects in the Layer can t be selected Let s apply a few transformations on the ground plane. You can trace areas where the land is raised and areas where the land is lower.

4 Select the ground plane, as an object (green selection). Go to Polygons > Edit Mesh > Split Polygons Tool Create a new free line that divides the grid and follows the brush stroke inside the landscape. Make sure that you create a new control point, (LMB), each time your new free line intersects the grid. Press Enter in order to confirm the new free line. Select all the polygons for one area, for example an area being raised and assign a new material. This material selection will help you selecting the area for later transformations. In this example, Green and Purple areas will be raised and become small hills. Red, Blue areas will be lower and become ponds or river beds.

5 Select a material color. For example the Lambert material with the Purple color, go to Polygons > Edit Mesh > Extrude, division = 1. Scale the extrusion in order to create smooth slopes on the sides of a hill. You can see the 3D Brush Strokes moving along with the extrusions. Render the scene.

6 Select a brush and edit the brush strokes in the Attribute Editor. For example, turn the Smoke brush stroke into trees by changing the Tube Shading color. Adding Twigs to a Smoke brush stroke can turn a couple of trees into a dense forest. Select a brush and edit the brush strokes in the Attribute Editor. Go to Tubes > Creation > Twigs Save your work as scene-paint Effects.mb Render the scene using the camera view point of your choice. TIP: Use the perspective camera in order to find the view point of your choice. In order to save the viewpoint, select the persp camera > Go to Edit > Duplicate. This creates perp1, a new camera. Rename the camera.

7 In Photoshop, you can save the rendered image with the correct pixel ratio. The pixel ratio is given by the dimension of the camera frame in Maya, for example 640 by 480 has a pixel ratio of This image will be used as a 2D Frame in Virtools. Part 2- Interactive character animation inside the rendering of a landscape (Virtools) Let s create walls for collision detection in interactive 3D. Select a curve from one of the brush strokes on the ground or create a new curve on the ground. Select the curve > go to Edit > Duplicate Special. Move the duplicate curve along the vertical axis. SHIFT select the curve and the duplicate curve, go to Surfaces > Surface > Loft, check Chord Length, Spans = 2, Polygons Save as Scene-2Virtools-Painteffects.mb

8 Clean up your scene before exporting the scene to Virtools. In Outliner, select each ground and each wall. Go to Edit > Delete by Type > History Delete brush strokes and curves. Make sure that all the 3D objects are polygonal Export the scene to Virtools.

9 In Virtools, import the rendered image of the Maya scene - resaved in Photoshop - as a 2D frame,. Select the rendered image in the resource folder > Textures > press CRTL and DRAG the image in 3D Layout. Add the scene from Maya including ground, walls, camera, lights. Go to Level Manager and make sure that each of them has an IC, Initial Conditions, checked. The 3D ground and the ground in the ground in the rendering need to match. This may require moving the 2D frame, the rendered image, on the Y axis. Please move the 2D frame, do not move the camera or the 3D objects. Create a group named obstacle that includes all the 3D Objects created as vertical obstacles in the scene.

10 Each 3D object of the scene: ground and walls, become invisible. Go to Setup > Attributes > Add Attribute > Visual FX > Z Buffer Only. In Schematics, create a script for one of the 3D Objects > add Building Blocks > Visuals > FX > Add Z Information. Go to the floor or ground Set Up > Add Floor Manager > Floor Attribute Add a character to the scene, scale the character and place it slightly above the ground. In Level Manager, check IC, Initial Conditions, for the character. Let s create a script for the character with the following four Building Blocks. 1- Characters > Movement > Character Controller > add character animations for wait and walk 2- Characters > Constraint > Enhanced Character Keep on Floor 3- Controllers > Keyboard > Keyboard Controller 4- Collisions > 3D Entity > Object Slider, select the group obstacles 5- Let s add a shadow to the character. We start by adding a Building Block > Planar Shadow to the ground. Go to Building Blocks > Visuals > Shadows > Planar Shadows, select the light and the color of the shadow matching the rendering of the scene.

11 The next step is to create an attribute for the character s mesh. Select the character, go to set up > Attribute > Add Attribute > Visual FX > Shadow Caster Receiver, Value > select the character s mesh that will generate a shadow. Playback the rendering of the character walking in the scene with a gray shadow projected on the ground of the 2D rendering of the scene.