ALAR 6712  Studio Workshop Spring 2010

Workshop 15 Notes, March 30, 2010

Editing by Projection, Fence Tools, Cutting Solids with Surfaces

PART I: FENCE TOOLS

Fence tools allow you to select a portion of a view window and to perform operations on it, such as editing, deleting, moving, copying, rotating, scaling or stretching geometrical elements.  You can also render a sub-portion of a window through the use of  a fence tools. The fence tool is projected into the view window to perform these various operations.

1. COPY AND CLIP OPERATION
Within MIcrostation V8i, start a new drawing, open the  Utilities>Auxiliary Coordinates dialog box. Use the save ACS  icon in upper left-hand corner and save the current default ACS plane as "base".


Turn on the ACS PLane lock by opening the padlock symbol at the lower part of the screen. Next, use the Solids Modeling, "Slab Solid" tool to create a solid slab on the ground plane.

Select  the front view (View 3) and use the "Define auxiliary coordinates by view" icon , highlighted in  the Auxiliary Coordinates dialog box below (7th icon from left-hand side), to create an ACS in the front view window.  

  

 Save the new ACS as "front" within the Auxiliary Coordinates dialog box.



Open the fence tools subpalette from the main task menu (#2 key).


Draw a "Fence"  in the front view window with "Fence Mode" set to "Clip". This mode isolates what's inside the fence from the outside.



Select the "Manipulate Fence Contents Icon"  (second icon in the Fence palette) andnthe "Move" option,  and enter two data points in the front view with to clip off and move upward the geometry that is encompassed within the fence. This is a quick boolean operation. Here we are working from a 2D projection of the fence onto the objects from the view plane.





Similarly, select the top view window. Select the "base" ACS form the Auxiliary Coordinates Dialog box,  and repeat the same move operation on the upper "Y" axis portion of the cubes from the top view.

The result of the preceding two operations is to splice the slab into four slabs. Note that the fence tool in the top view operates on  upper visible slab as well as the occluded lower slab in that view. That is, the fence projects the operation entirely through every object in its pathway in that view.

2. STRETCH OPERATION

Re-select the front view, then select the "front" ACS in the Auxiliary Coordinates dialog box, and place the fence over the slabs in the lower portion of the view window.  Next use the "Manipulate Fence Contents" and  "Stretch" tool option (shown below)  to change the height of the cubes on the ground plane..

Once again, the fence projects the operation entirely through every object in its pathway in that view and they are stretched to have a larger "Y'" dimension. Note that a truncated cone (not shown) in similar situation would also have stretched in a tapering way preserving its tapering geometry. Similarly, other objects will also stetch appropriate to their geometry.

3. NON-RECTANGULAR FENCE

Select the "Front" view and then the "front: ACS from the Auxiliary Coordinates Dialog box. Next, select the" Fence" tool,  change the fence  type to "Shape",  and draw an arbitrary polygon over the front view.

Zoom out of the  "Front" view and use the "Manipulate Fence Contents/Move" option to clip the arbitrary shape to a location above the slabs. Note that the operation cuts the arbitrary shape out of the cubes and moves it above them.

3. RENDERING WITH THE FENCE TOOL

In View 2, draw a "block" Fence over a portion of the view window. In the Visualization task, adjust the solar lighting using the W1 tool,  select the "Render" (Q1)  tool, and choose the "Fence" option. The result is that a smaller sample portion of the view window is rendered. This can be a very efficient way to sample the rendering quality without having to expend much greater time in testing the entire view window. Note that rendering 1/4th of the view window in Ray Trace will be significantly faster than doing the whole view.

Note that the Render dialog box also allows you to render individual objects in several render modes, such as Phong or Smooth shading. This is achieved by selecting the third icon in the "Render" dialog box as depicted below. However, this doens't work in Ray Trace mode (since the rendering algorithm is based on backward tracing of rays for every pixel in the rendered area).

PART II: EDIT BY SURFACE PROJECTION

 

Erase the current elements in the model, and place a rectangular block and a bspline curve in the ground plane. Next, within the Solids task, use the projection tool (T1)to project the bspline curve into the vertical direction.

Place a slab in the model so that it is fully encompassed by the new surface.



In the Surfaces task, sleect  the "Trim Surfaces" tool (S1) and select the "Trim 2nd" option, then pick the surface first and the slab second. Enter an additional data point in the view window to initiate the trim and a fourth data point to confirm it.  Note that a portion of the slab is trimmed away.
 

The reverse part of the slab is trimmed away if the "Flip 2nd' option is turned on.

The surface trims the slab according to the direction of its surface normal vector (the positive side of the surface). This vector can be reversed through the use of the "Change Surface Normal" tool(S6) in the "Surfaces" task(image at left below). Selecting the green surface normal arrow will reverse its direction. Completing this step and re-doing the trim surface operation will reverse the portion of the slab that is trimmed away.