By combining 3d scanning, 3d digital modelling, and 3d printing, it is possible to create amazing and surprising effects, objects that can seamlessly blend between reality and imagination. In this tutorial, I describe the process of making a full colour 3d printed object that seamlessly fits on to a real sandstone wall, producing the illusion that the wall is built from pieces of lego. But the techniques described  have a more general usefulness, almost limitless potential, and  are easier and less expensive than you might think!

Staring with a real physical object, in this case a sandstone brick wall, I create an inexpensive but high quality digital 3d scan using a stills camera and the program Agisoft Photoscan. I then model the lego brick shapes over this scan using 3d software, I make this model fit perfectly onto the scanned wall by using boolean subtraction, I add colours clone stamped from the photos, correct the scale, and finally I do a colour 3d print, which fits seamlessly onto the sandstone wall, producing a novel illusion that would be difficult to achieve by other methods. 

Step 1: 3d Scanning

3D scanning is traditionally achieved with prohibitively expensive laser scanner hardware. However, recent software developments have opened up the possibility of acquiring a similar quality of 3d scan using just a stills camera. I used the program Agisoft Photoscan, which I highly recommend, and a cheep point-and-shoot canon camera. Agisoft Photoscan is easy to use, and not terribly expensive. There are also some free alternatives, ScannerKiller, and 123d Catch.

I took around 29 photos from different angles, and the software automatically derived a 3d mesh from those photos. I chose a sandstone block with a chipped off corner, so that my 3d print could fit into empty space left by that missing corner. The process of using agisoft photoscan is very user friendly, but poor quality photos will tend to result in a less detailed mesh with more artifacts. Try to avoid taking photos that are poorly exposed, or out of focus. The object should remain completely still while you take the photos, if it changes shape or moves it's position then the reconstruction probably won't work. The photos should not be taken from dramatically different angles, there must be some level of overlap and similarity among the photos, or a mesh cannot be derived.

I generated the mesh with Target quality set to Medium, and Geometry type set to Smooth. I generated a texture at 2048*2048 using Orthphoto Mapping mode, and Mosaic Blending mode. Then exported the mesh as an .obj file, and the texture as a .bmp.

These programs tend to work best with very textured objects. The texture gives the software features to lock on to. To get the Best results with smooth untextured objects you may have to apply a random blotchy paint pattern. Blotchy facepaint works really well when scanning people, though it may look rather silly! Shiny objects can also cause problems, because they look different from every angle. Shine may be reduced in a number of ways, talcum powder, dulling spray, or it may be filtered out using polarizing filters, one on the lens, and one on the light source. The filter should be rotated until the shine disappears. Large polarizing filters can be bought online, and it's possible to get very cheap small polarizing filters by cannibalizing the lens from a pair of 3d glasses. Some light sources such as the sky, or LDC screens, are already polarized, so they won't need a filter.

In many cases it is possible to approximate tiny micro details from the scanned object. By applying a "high pass" filter (in PhotoShop, or an equivalent image editing program) to the colour texture map one can create an image that may be used as a bump or displacement map. The results may not be perfectly accurate, but in many cases this will result in a visually convincing level of very fine detail.

<p>Wow, I did it. Looks pretty cool!</p>
<p>Truly inspired project; great idea and execution! You've definitely given me some food for thought.</p><p>I've found that PhotoScan does a very nice job of capturing people as long as you have a good lighting setup.</p>
That's soooooooo cooooolll!!!!!!
Wish I had a 3d printer my house would never look the same again :-)
Brilliant! Great idea.
This is insane. Awesome job!
Really stunning and an incredibly unique and interesting idea. The colour matching on the lego blocks on the steps and the dripping bricks really surprised me. <br> <br>If you don't mind me asking, you mention that you gave the printed pieces a sand with some very fine paper and then gave it a coat of thin superglue before then giving it some matte. <br>Why did you give it a superglue layer before the varnish (would the varnish have not sufficed on it's own)? <br>Did you just use regular superglue from a tube and then use a brush or did you thin it with something? <br> <br>Really appreciate any input you have, and again, really awesome work.
Fantastic! <br>What 3d printer did you use? <br>and about the colors... the printer already make the 3d object and colors, textures?
Brilliant work!
Are you joking? That is the coolest thing I have EVER seen!!!
dude you got skills im speechless
This is brilliant
Thats cool, I never knew that 3d scanning with photographs was so precise. You could do some really cool halaween pranks like this.
Awesome idea, awesome tutorial! And that is some INVALUABLE advice on scaling everything by 39.37%. <br> <br>This is so creative man, I love it!
Thanks Deej!
I love this! What a nifty idea.
wow. Nice idea. Briliant. Love the lego stone

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