JYM,
You can create a grid surface using the contour lines as the "template" for the grid. The "Draw/Surface Connect" function allows you to define the number of intermediate "breaks" or lines between the original lines and the number of "planes" along each contour line. The result is a fishnet grid surface that can be shaded. See the attached pictures.
However, it is not as easy as it looks!
1. You can create grids between lines (V) and curves (C). Normally curves will produce better results.
2. In the "contour grid" image the red contour curves were drawn by setting the starting points randomly. Each curve is defined by a collection of sequentially numbered points. With "Surface Connect" the first point (1) on each line is the starting point for grid creation along the curve. The program connects the numbered points on each curve with the same numbered points on the other curves.
As you can see the points on the red curves do not align so the resulting grid is twisted and distorted into a wrinkled surface.
The points on the blue curves are all ordered in the same direction, with the first points (1) aligned. The result is a smooth grid that shades properly ("shaded contours" image).
It also helps if each curve has about the same number of points, and the smoothest and most orderly grid results if all of the same numbered points on each curve line up nicely.
Also, you MUST select each curve near point 1 and in the same direction around the curves from point 1. Failure to be meticulous about this can produce some extremely distorted grids!
If at first you do not succeed, UNDO, and try again!
3. Notice the hole at the top of the "hill." You cannot create a grid between a curve and a point mark. The innermost element must be a curve. Make the innermost curve relatively small and then fill in the hole with a plane (P). After all grids and planes have been created, select them (but do not select the original curves!) and use "Solids/Solid Define" to make them all a solid. This will cause the transition between the grid and the plane to render smoothly.
4. What about the parts of a rectangular surface outside the closed contour curves? This is VERY tricky!
In addition to "Surface Connect" there is also the "Surface Patch" function.
"Surface Connect" works well with open ended curves and closed loop curves that are more or less parallel, like the loop contours on a hill. It does not work with irregular areas.
"Surface Patch" works with a collection of lines and curves that encloses an irregular space. You can use this to close the gaps between the edges of the "map" and the closed contour curves. Again, this is very tricky, and can be quite frustrating until you eventually figure it out.
Basically, you draw three or four separate lines/curves to enclose the area. Then start "Surface Patch" and select the lines and curves. You have the option to define the number of planes "across" and "down." I have never been able to figure out what "across" and "down" mean! They define the number of planes in perpendicular directions across the grid, but how "across" and "down" are applied differs depending upon the first line/curve you pick and the order you select the other lines. Just think of it as random, and if the grid doesn't look right try again by selecting a different line first and changing the order you select the other lines. Good luck!
Patience is a virtue hard to come by!
In the "contour map grids" image (with four instances shown) the original lines and curves for a map are shown in blue in part 1.
In part 2 I have recreated the original light blue grid with the closed contour curves using "Surface Connect." I have also added a plane at the top center. Around the edges I have used "Surface Patch" to make orange grids at the corners.
5. When filling gaps between the original closed curves and the surrounding irregular areas, you cannot use the original closed curves - the grid will stretch all the way around the original curve. You must create new curve segments along the part of the original curve you want to use.
In part 3 I have created four new curves (two green and two red) where the original outermost blue closed curve was. Again, I was careful to set the points in the same direction as the points in the original closed curve. Then I used "Surface Patch" to create the corresponding red and green grids between the outer map edge and the closed contour curve.
Part 4 shows all of the different grids placed together.
6. The "contour map shaded" image shows the grids in their original colors on the left, and all grids shaded light blue, collected and defined as a solid.
As you can see, the result is not perfect. But it is a start. Here are several things to consider.
First, the gaps between the inner grid and the outer grids are the result of not having the same number of points in the lines used to define the grids.
Second, even though all grids are combined as a single solid, there are sharp transitions in places where they do not blend smoothly as a single curved surface. This is because there are not enough individual contour curves forming the grids surrounding the inner grid. The program needs more curves, at proper elevations, in order to make all of the grids align correctly.
You can use the initial set of grids to create a new set of contour curves, and repeat the process until you get a smooth map surface.
When drawing curves more points are better than fewer points.
Phil
