When I designed and built my own CNC, this is exactly the type of project I had in mind. A chance to play with forms and test ideas, bringing things to life that would otherwise just live in my sketchbook.
In this Instructable I am going to show you how I simulated water drops in Photoshop for shape generation in Rhino 3D and eventual output to my DIY CNC. This technique could also be applied to any 3 dimensional artwork that you can generate using light and dark to define object depth.
I am using water drops to show the advanced ability using layers to simulate the interaction of waves with each other resulting in a very believable final model.
The software used:
Step 1: - 23 Setting Up the Simulation in Photoshop
Step 1: To begin you will need to find a source image of water drops so that you can study the relationship of the wave spacing and intensity. You might find one that is better than the one I used.
Step 2: Bring that image into Photoshop and draw vertical lines at the peaks and valleys of the waves.
Step 3: Select the Gradient Tool.
Step 4: Click on the window in the options bar that shows the active gradient ramp. This opens the Gradient Editor Dialogue box.
Step 5: Click underneath the gradient bar to add more color swatches. Add as many swatches as you have peak and valley lines.
Step 6: Expand the window horizontally until the gradient bar spans these vertical lines representing the peaks and valleys. Arrange the newly created swatches inline with your reference marks.
Step 7: We will now define the colors of these swatches keeping in mind the visual reference of the source water drop image. We will be defining the depth of the waves based on white to black gradient, so we want to start with a base color of 50% on the CMYK scale. Double click on the swatch to open the color picker dialogue box.
The values I used were the following from left to right.
10 | 60 | 10 | 70 | 20| 70 | 25 | 60 | 45 | 55 | 50
another way to look at this to get an idea of relative amplitude of the waves...
+40 | -20 | +40 | -30 | +30 | -20 | +25 | -10 | +5 | -5 | 0
If the rings are a long way from the center, the first value might be 50 (flat) and the swatches would slide farther to the right on the scale and remain relatively unchanged.
Step 8: We will now set a transparency ramp for the new gradient. Click above the gradient scale to create a new swatch and move it toward the end of the scale. You should now have 3 swatches above the scale. Set the two on the left to black (opaque) the far right one to white (transparent) this will end the gradient when it reaches the edge of our ripples.
Step 9: Click on New to add the newly created gradient to the list of Presets.
Step 10: Now you will need to create a new Photoshop document. Click File>New and in the New Document Dialogue box, input a width of 10000 pixels and a height of 5000 pixels. And make sure that it is RGB color. Rhino will not read a CMYK formatted document.
Step 11: Insert a new layer in the layer control box.
Step 12: Using the grid and guide lines, make a box in the middle of document select it with the rectangular marquee tool. You could do this image full bleed, but I prefer to have a little elbow room when moving things around.
Step 13: Set the color to 0% C 0% M 0% Y 50% K and bucket fill the rectangle.
Step 14: Insert new Layer.
Step 15: Select the Gradient Tool, choose Radial Gradient in the Options Bar and make sure your custom preset is selected.
Step 16: Click in the center of the document and drag away from the center, releasing near the edge of the field of grey.
Step 17: Now you should have what looks like a target. We now need to set the Opacity and Fill values to 50% so layers will mix when overlaid.
Step 18: Select the move tool and while holding down ALT, drag another copy of the layer made in Step 16. Note the interference produced. Also note that where two light area cross, the image gets lighter and where two dark areas cross, the image gets darker.
Step 19: Make more copies and scale and compose as much as you like.
Step 20: When you are done, select the field (or part of it) and select Edit>Copy Merged.
Step 21: Go to File>New. The values should already be automatically set for what is on the clipboard. Make sure it is RGB mode and Click OK
Step 22: Go to Image>Auto Contrast. This takes the whitest area and makes it white and the darkest area and make it black.
Step 23: Save this image.
Now that we have the final image, we are ready to bring it into Rhino and use the gradients to define 3 dimensional geometry for rendering or to make an actual object.
(If you wanted to do a 3D laser engraving of this image, you are already done as most laser cutters support raster engraving.)