How to find an angle and a distance for clicking picture of a distorted artwork to achieve 3D effect?

Question

If you know about 3D pencil artworks, you would know people draw it distorted (generally length is enlarged i.e., stretched from bottom to top) first and then click a picture at some angle (30-40 degree, depends on distortion and actual angle of the subject in reference image).

Now, I created an artwork, but I realized (I'm not 100% sure, but have belief after seeing the output) this today only that you just don't need unifrom distortion of an image, it should follow a geometric progression like stretch.

Now, what I mean by geometric progression of stretch and normal stretch, I kindly request you to just have a look at the details & image at my this question.

Now, I made the uniformly distorted artwork. So the problem is:

The scorpion is bigger at bottom and the top part is smaller when compared to the reference image (please see photos below).

Reference:

Artwork (Photo at angle):

Artwork (Photo from top, actual distorted view)

**What I guess is, if I had drawn it distorted in an geometric progression, the result could be better in terms of a match with reference image. **

I tried to test this thing later by doing a simple line artwork, more distorted at top and less at bottom, and result was satisfactory.

Now, the artwork is already done, it can't go waste. So at what angle and what distance (approximately) I should keep the camera to achieve a closest result, where my artwork seems to be similar to the reference in terms of angle and proportions, when the artwork is placed on a horizontal surface?

Answer 1

As this is the photography forum I will try to make a good approach using one. You need a camera with some kind of live view preferable.

1. Get a tripod and position your camera pointing to the sheet of paper. I think a lower angle than the one you are using is probably more dramatic.

2. Prepare a grid. Take a piece of cardboard, pets say size tabloid or A3, and cut a hole inside. Make some markings, let's say every 2.5 cm or every inch, and tape some thread.

3. Put the grid parallel to your camera. Now try to find the matching spots where the thread crosses and draw that grid on the paper.

Now you have the deformed grid with the correct perspective for that spot on space. Use it as a template for the deformation of your drawing.

You actually can do the same with a full drawing, for example printing it on acetate for retro-projection, or use a projector instead of a camera.

Answer 2

Distance depends on focal length.

Instead of taking a photo, you can achieve the same result by scanning the picture and applying a perspective transform in Gimp/Photoshop. This is likely going to be faster.

Without geometric markings on the sheet you'll have to eyeball the best shot. IHMO the best way is to clip the drawing on a board, put the camera on a tripod or any fixed position and shoot the board at various inclinations.

You can make markings with Gimp/Photoshop:

• Take your "from top" photo in Gimp/Photoshop
• Apply the perspective tool to get the required effect
• Draw two vertical lines on the picture
• Apply the perspective tool in the opposite direction, making the sides of the paper vertical again (the line you drew won't be vertical)
• Print the result (without a printer you can also using tracing paper on your screen: you just need the extremities of the lines)
• Put the print out on the board.
• Figure out the board inclination that make these lines vertical in your viewfinder
• Replace with initial drawing and shoot