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For mothers day I wanted to create something very unique for my wife. So going along with the same idea as my previous instructable Generate-a-unique-shadow-casting-sculpture, I decided to make something a little less tangible, but even more intimate.
This personalized candle holder displays a silhouette of my family on the wall and some text on a table using only the light from a little tiny votive candle. If done correctly, the shadow will be indifferent to the specific height of the wick and flame (within the typical sizes for votive candles that is).
Instead of hanging a photo with nails, or a mural with wallpaper/paint, the candle holder...and thus the shadow, can be swapped out easily for different occasions, even during the daytime hours!
Suggestions: Free Software: Picasa Autodesk 123D and Catch Requirements: 3D printing service Please note that the 3D printing is essential, because no other practical solution exists for creating such a structure. NONE!
Also note that I rely heavily on annotating my images in this instructable since the easiest way to see what Iím doing is with a screen capture (Shift-Command-3), upload, and click for an instant note. Except for a few rarities, every image is tagged somewhere, so if you see a blank one, look for a itsy square crammed at the top of the image. Sometimes, I see this happening on both mine and otherís Ďibles and I donít know why. Clicking on the next image and then going back sometimes repairs the problem.
My system: MacBook Pro
Parallels 7 running Windows 8 (AutoDesk is working on a Mac Version of 123D, but not yet out)
Step 1: Decide on an environment for your shadow
Most shadows have a common feature in that they all consist of an outline that's darkened in the middle. With reflection, multiple or broad light sources, soft edges, or translucent materials, other effects can occur, but for this project we will consider only a well defined shadow shape and an opaque blocking material.
The lighting and environment all need to be thought through and will determine the form of shadows that you can create.
You are not limited to a single surface. Actually, you can project a shadow through multiple rooms in your house that only makes sense from one perspective if you like (example: http://www.archivenue.com/wp-content/uploads/Geometric-Illusionary-Perspective-Paintings-1.jpg). Cast it on the ceiling, or both the table and wall simultaneously as I did.
Consider permanent obstacles, such as the chair in my photo...or dynamic ones, such as a person if they happen to sit in said chair.
Step 2: Design your scene
The most practical tool for starting these kinds of modeling endeavors, is with some real world landmarks so you can navigating through the virtual model as you create it while having something tangible as reference. Physical numbers used in scaling objects is necessary, but having a identifiable object in your scene makes things so much easier.
I used 123D Catch for this. Application notes:
Step 3: Detail the shadow drawing
Since mother's day was approaching, a likely subject was a family portrait. Easy enough choice, but to make my sketching a bit easier, I first used Picasa to bring about more contrast for my shadow edges.
Also, the objective is to bring out recognizable features in binary (shaded or unshaded), that are normally easily discernible in color. By post processing your images, it's easier to see what is important to trace, and what can be left out.
The order I used:
Step 4: Fix your model's coordinate system
Create a new 123D file by opening the .obj scene created earlier in Catch if you performed that step. If the mesh was not scaled already in Catch, you need to do that at this step. I knew that my final solid should be under 3x3x3 inches, and my votive candle has a diameter of 1.5 inches, so I drew a three inch square and 1.5 inch inscribed circle and then scaled the candle to fit the circle. I also knew the height of the wick as a backup. It is best to scale it in Catch first though. They have videos on how to do that here.
You may adapt this whole instructable to suit your project, but I reference the base of the candle axis as my 0,0,0 point.
Step 5: Create a canvas for sketching
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Construction of work axes and planes are your best friend for this project. Understanding how the various options can clarify your virtual environment will make your experience less frustrating. I used an offset plane to place my canvas on. For the portrait, I wanted to cast the shadow on my wall, so I needed a plane parallel to the xz plane and 70 inches away. I turned off the visibility of every other component in 123D and then placed my canvas using the .png image created with Picasa.
Step 6: Work the Working Axes
Although you CAN loft from a feature to a point, I always had bad experiences with it. Some of the steps later described here are a result of trying to fix a point lofting error.
So, the safest way for more complicate shadows involves creating a work axis connecting a point light source to a distinctive point in your sketch. I use at least four: bottom corners, apex, and some other feature, like an earlobe. These will allow you to copy your portrait sketch, shrink the copy and position it along the optical axis perfectly. The work axes should go though the identical points on your copy as on your original. Nudge the copy until it does. Make sure you rotate around and the work axes still go though the correct points.
The copy must lie within the part that will create the shadow!
I believe that I eventually scaled my copy to 0.1 or .06 of the original.
Step 7: Add Any Additional Shadows
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Text seemed like a cool idea, but it didn't go as smoothly as I dreamed. As of this writing, 123D scales text not by points or pixels, but by whatever units you are working in. So, naturally, I picked my font with a scaling of 8.....inches! Ah!
With eight as the lowest value that I could choose, the letter "H" in Happy Mother's Day was already twice larger than the entire sculpture. I wouldn't be able to fit "Happy" on my dinning room table. So I conceded to sketch the best I could the words I wanted to display. They also aren't floating, but grounded to the candle holder. This means that the shadow traces back to the base of the candle piece. Floating is more challenging because your support material will create a shadow. It must be included, and I didn't want to work that out at this point.
Use work axes the same way to position a copy of the text for tracing the projection backwards to the candle flame.
Step 8: Loft, Loft, Loft
This would be the end if the Loft function didn't exist. What a sad world it would be. Lofting provides a means of creating surfaces and solids with complicated features or transitions using only boundary profiles. In this case we use the original and copied sketch as the profiles. Make sure you do not rotate the copied profile in any way prior to lofting.
Step 9: Frame the Candle Holder
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Although I show pieces of the solid at various previous steps, I haven't described how to construct the actual printable candle base yet.
Step 10: Finalize the Full Shadow Volume
Riddle #1: Does a shadow have a volume?
Riddle #2: Does the light have a volume?
Riddle #3: Could you subtract one to get the other?
Up to this point, I havenít explained how the lofts modify the scatter of posts that will ultimately create the desired shadow. The sequence: Create->Combine->Select Single body->Select Multiple Bodies->choose Intersect->press Enter will remove all of the material except where the multiple bodies overlap with the single body . So you select the Solid candle holder as the single body and then all of the lofts as the multiple bodies part. The problem is quickly evident if you only select the lofts for your multiple bodies portion. You will retain the light blocking posts, but without a base to support them!
The different loft segment faces are separately selectable, just as in the first above image in this step. You can "fill out" the remaining volume between the lofts by extruding these faces some exaggerated distance. The overlap is important, not how far beyond its extended. If you understand the rational behind what the lofts are for, and why we can use them (for angles, not absolute scale), then you will easily see that an extension in the right direction will have no negative impact on the final product.
Again, for additional explanations, review the uploaded images with notes.
Step 11: Connect Disconnected Pieces
The unfortunate part of my construction choice is that while I wanted the final product to be abstract enough to prevent guessing the shadow, by using posts instead of a solid block of material, I leave a few danglers after the Intersection function is executed. This is because horizontal holes larger than the diameter of a post will sever the upper portion of the post from the base. You could print it this way, but after washing away the support material, you would be left with a tray full of "broken" pieces. Not good. Here was my approach:
If you made vertical posts like I did, then think vertically, 'what posts are affected with an horizontal cut?í Then,
Step 12: Command P
Although it shouldnít be necessary at this point, you must ensure that all of the items that you want printed are combined into a single piece. This is accomplished as before with the Combine->Join function.
Export your file as a .stl
Currently, in 123D, you must first sign in with a username and password to enable all of the Save As options.
Now you are ready to print. Several 3D printing services are available online, or if you are lucky to have access to your own printer, you could print out several versions of your own Super Personalized Candle Holder or make them for others.
Thanks for your comments on this Instructableís clarity and room for improvement.
I will upload an image of the actual shadow as soon as one is available. The speedy draft print didnít include the internal cuts that require higher resolution.