CGS 3220 Lecture 17 Subdivision Surfaces

Transcription

1 CGS 3220 Lecture 17 Subdivision Surfaces Introduction to Computer Aided Modeling Instructor: Brent Rossen

2 Overview Converting from polygons to subdivision surfaces (sub-d) Modeling with sub-d using polygon proxy Adding detail Using creases Basic bump mapping Cleaning the topology of sub-ds

3 Modeling a Gas Can Create -> Polygon Primitives -> Cube Shading -> Smooth Shade All Width: 4.5 Height: 5 Depth: 3 Subdivision Width: 6 Subdivision Height: 1 Subdivision Depth: 3 Translate to above the grid, y: 2.5

4 Convert to Sub-d Modify -> Convert -> Polygons to Subdiv Press 3 to display smoothly Rename to tank Subdiv Surfaces -> Polygon Proxy Mode Outliner -> Display -> Shapes: On tankshapehistpoly is created, this is for editing using polygon tools

5 Tweak the Vertices We ll be using the marking menu for quick selection RMB on the tank Select Vertex from the marking menu From the front view, select the vertices and tweak as in the image

6 Extrude Polygonal Faces RMB on the tank and select Face Select the central top face where the spout should be Edit Mesh -> Extrude Extrude the face upwards as in the image

7 Extrude the handle Extrude the handle as in this image

8 Merge the handle Delete the two faces of the handle that are facing each other Go to vertex mode Using the move tool, hold v and snap the corresponding vertices together Go back to object mode Edit mesh -> Merge

9 Extrude the air valve Select the face at the back of the handle Do a first extrusion and scale the face down Do a second extrusion to extrude the valve Make sure you like the shape

10 Tank Holes Using extrusions, create holes in both the spout and the air valve Once the holes are made, delete the bottom face to create the openings Save

11 Standard Mode Now we ll make use of some of the sub-d properties to achieve a greater detail Particularly useful are making creases in edges or vertices When you define an edge or a vertex the underlying geometry is changed to create the crease

12 Leave Poly Proxy Select the tank Select Subdiv Surfaces -> Standard Mode from the Surface menu set This will remove the poly proxy, but with sub-d you can get it back! Just use Subdiv Surfaces -> Poly Proxy Mode RMB select Edges Select the main edges defining the gas tank Subdiv Surfaces -> Partial Crease Edge/Vertex

13 Full Creases Select the outer and inner edges of the spout and air valve Select Subdiv Surfaces -> Full Crease Edge/Vertex This should give the flat edges as shown Adjust vertexes as necessary Make the handle and base of the spout and air valve partially creased

14 Texture the Tank Texturing is similar to using UV on Polygons Switch to hypershade/persp layout Create a Phong material and color it red, assign it to the tank

15 Bump Map & Caps Automatic map on the sub-d faces Create a bump map using the 3d paint tool, then refine in 2d image editor Make the caps out of polygon cylinders Freeze transforms group the objects Delete history Optimize scene

16 Model a cliff Another use of sub-d surfaces is making terrains Create -> Subdiv Primitives -> Plane Scale to 100 in all axes RMB on the plane and select vertex Move them as in the image

17 Display Finer Details RMB on the plane and select Display -> Level: 1 Select the finer vertices and move them forward to produce cliff edge definition as in the image With those vertices selected Subdiv -> Refine Selected Components

18 Refine the Cliff Edge Select Edges and move them to refine the cliff edge Move some vertices down under the cliff and set them to Full Crease as in the image on right

19 Lower Display Level RMB and select Vertex RMB on the plane and select Display level -> 1 Adjust the vertices and watch how the finer levels move Refine the landscape to create valleys and hills Try to hide the exterior edges by moving them down Test render

20 Texture the terrain Using the 3D paint tool texture the landscape using paint effects brushes and colors on a lambert Sometimes unnecessary geometry is added Subdiv Surfaces -> Clean Topology

21 Wrapping Up These processes can be used to model organic forms Create them like a poly or nurbs, then refine them with creases