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Bio mechanic model by Alessandro Tessaro

Sub-division surface modeling with Realsoft3D REALSOFT SALES AND SUPPORT @ SCENE
From where the last tutorial left off, run the mouse cursor over the SDS in edit mode. Faces are highlighted to show which face will be selected when the mouse button is clicked.
Select the face which corresponds to the left face relative to your view arrangement. A handle appears and the face is highlited.
Press the CTRL key and drag on the blue handle to extrude a face out. You will see that most common SDS modeling operations are done using the handles together with key modifiers.
Repeat this process of extruding faces a few more times to get a very basic car shape.
Very important for SDS modeling -> look at the underlying smooth nurbs mesh that results from the SDS control cage. Here we see the pattern that results from a 'T - intersection' of edges.
You can quickly change between face/edge and point editing using the compass menu. Here is the top view about to go into point editing to drag a few points there to get the desired shape.
Tip: You may want to go to the view properties and change some settings for that 'camera' view that were set up in the last tutorial, if you prefer modeling SDS in orthographic views only.
Taking a view from the side of the car, drag-select faces on the lower half and use the Tri/Quad tool in the control bar to subdivide these faces.
Looking from the side of the model, use the knife tool from the control bar to split the edges at the top.
See how the knife tool splits all edges that you draw through, and creates new edges joining the intersections. Very useful.
Go into points mode and select the points shown here.
Now, again in the control bar, use the ADD tool to create a new edge between these selected points. Repeat this process for the other side of the car.
Now look again at the 'flow lines' of the nurbs mesh. Much more tidy and appropriate for this part of the model. After some practice, you will get a good 'feel' for how to contruct SDS control cages which result in nurbs meshes that flow nicely with the contour of the shape.
Now to make a simple bumber shape. Select faces shown. A tip for selecting backfaces without spinning round to the other side of the model is to use the comma ',' key while selecting. It cycles through all faces from back to front.
In the control bar, hit the small triangle next to the extrude tool to get options for that tool. Select 'Extrude Face', and under the 'Action' tab, select 'Selected face vertex'.
Split the car down the middle using the knife tool with grid view and snap on. This gives a little extra detail to play with. To perform a straight-line knife uncheck the freehand option in the toolabar after selecting knife tool.
.. and this is the result. The extrude and bevel tools here are provided when extra control is needed over just performing those operations with the handles as was done previously (with Ctrl-drag on handle).
Use the compass (same as before) to go into edge mode. Select the front windshield edge and bevel it by using crtl-LMB drag up on the handle endpoint. You can perform this on both sides at the same time by selecting both edges and using bevel on one edge to get things done faster.
Like you bevelled the edges before, select the faces on the windshield and bevel those to give more control over the shape there.
Knife again as shown. Notice how features get a little sharper as more detail is added to the SDS cage. The resulting geometry of all SDS cages is resolved with clever use of continuous nurbs patches.
Go back to face mode and select as above - this face already provides a reasonable starting point for making the indented wheel arch.
There is a very powerful way to achieve sharper definition to edge/face and points. Each face/edge and point in Realsofts SDS cage can be set a weight value. This is due to the underlying nurbs set being a complete weighted NURBS implemetation. Notice here the the bumber is currently quite smooth where it joins the main body.
Go into edge mode and select all the edges where the bumber shape meets the car body. To help with this, the hotkey SHIFT adds selections, ALT removes, and SHIFT+CTRL toggles.
There are a few ways to sharpen at any value you want, but for now a quick and easy method to sharpen these edges is just select the dropdown list in the toolbar and change from smooth to sharp Do a quick viewport render - '0' (zero) shorcut key to see the result clearly.
Use the knife tool to make a few new points on this face close to where the inner part on the wheel arch is.
Use CTRL-LMB drag to extrude this face inwards. This gives nice joining faces at the sides and top, but leaves us with some extra faces at the bottom which have to be fixed up. There's probably a better way to do this but I chose to just go ahead and make the extrude and fix up the details later. So, to fix up...
You will see a huge hole in the mesh now. That's fine. Look at the bottom and notice that there is actually another face there extending to the outer edge of the car.
First select this face and destroy it using the tool shown above. Destroy removes the face completely, while 'Delete' will create a new larger joining face.
Select points and merge as shown above. The shorcut key to merge points is SHIFT-M.
'Destroy' the large face at the bottom.
Now you can see that a nice framework of points exist at the correct place (there were many other ways this could have been done).
Select the points in a cycle and add a face.
Basic shape done.
Move a few points around to get the desired shape.
(I won't detail the wheel modelling procedure I used.. it's just using the method I copied from Hellmut T's wheel tutorial.)
Here's the finished wheel and a few more point adjustments made to get a nice circular wheel arch matching the wheel.
For some quick and easy texturing, I just selected faces and dropped materials straight into the viewport. Here the standard rubber has been dropped onto the bumber faces and is viewed in OGL.
Another onto windshield faces
A few more points are added with knife tool, and various points are moved around to get a 'front' and 'back' for the car.
Version 4.5 provides a mirror tool based on construction history for modeling opposite sides at once. This one was just cut in half, mirrored and joined with the 'join faces' tool.
Standard metal and rubber for the wheels and tyres.
.. and a few more materials to suit your taste.. or whatever ..
Using the basic SDS car body shape, this variation adds some nurb modeled trimming and booleaned-out windows. Nurb objects can be used to cut out of SDS shapes & analytics, and visa-versa quite interchangably.


Page updated on Tuesday, 25 February, 2003 . For feedback / model submissions or articles - please email us.
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