Missing dimensions compensation for 3d modeling - Photoshop method


Looks familiar? Well, it should for those who work with interior 3d modeling and rendering often. Besides the apartment furniture plan, this image represents the actual wall dimensions. And, as you may noticed we have only two sizes indicated. Such deficiency creates a reasonable question - Where do I, as a 3d modeler, get all other sizes and how much work needed to model this??

Of course, I'm talking about the plans, given to you in raster image format.

Some say it is rather professional ethics question, that you must get all details about project from your client before you accept the work at creating 3d models and their render. But, unfortunately, in the times of wide popularity of 3d visualization and freelance working we not always have such choice when we can demand thoroughness from our client. Even if this is your necessary working conditions, some client could simply have no ability to provide you other info.

The long and short of it, this situation is possible. And before you're upset, check out the quite accurate and sufficiently quick (1-2 minutes) method of compensating the missing dimensions on the plan in 3d.

This is how its made:

  1. Copy any present dimension image to clipboard from original image
  2. Create new image and copy to clipboard its resolution after changing its height to the showed on plan value
  3. Replace the original image's resolution to previously obtained and copy to clipboard the resulting dimension
  4. Make the plane in 3d exactly that copied size
  5. Apply the original image as a texture to that plane

Not very understandable? Then welcome to the following explanation :)

As you can see, we have one vertical size to the right and one horizontal size to the left hand of the plan.

First, we got to set the image 1:1 aspect ratio. We want to do this because it is lot simpler to map the square image to square 3d plane in 3ds Max (or any other 3d software), then to watch the right proportions when both the plane and image rectangular.

The most simple way to do this in Photoshop in s to use the Crop Tool. Press Shift and drag the cursor along the image. When you reach the closest border, release mouse button and then drag it again - this way you will be able to crop the image "out" of the borders.

We get the square image now.

Next thing to do is to set the right pixels size. By right I mean the size, which would be nicely displayed in 3d software viewport. In particular, 3ds max makes the horrible interpolation of textures, if they are not 512x512, 1024x1024, 2048x2048 and so on.

NOTE: 3ds Max users, make sure you have the maximum values in the 3ds Max menu > Customize > Preferences > Viewports > Configure driver > Appearance preferences > Background texture size & Download texture size.

 There was a surprise to me to discover that 1100x1100 texture looks worse than 1024x1024 one in 3ds Max viewport.

When we have the "right" size image, which is usually multiple of 1024px, we can start to calculate the overall size of the obtained image in our measuring units. Having that number, we can set it to our future 3d plane in 3d viewport and get the exactly corresponding dimensions on image and the 3d plane.

So, next we got to select the preset dimension image. You got to choose the biggest size to take the resulting size error to minimum.

Once we've selected it, we copy it to clipboard.

Create new document, which will be our temporary buffer,

By default, Photoshop creates document with size that exactly match the one in clipboard.

And then paste the previously copied dimension image.

To get something like this:

So we have an image of some exact dimension. The essence of thick step is to now set this image the same dimension (in this case Height) and grab the resulting resolution (DPI) to ours original image. As you may know, all images have the only pixels as a true measurement. The DPI as well as width and height are the relative virtual values, used only for reference. We gonna use this sometimes confusing feature for our benefit.

Call the Image Size window,

untick the Resample Image checkbox. This will allow us to play with those relative values without changing actual pixels. As you can see on screengrab below, the pixels now blocked from altering.

Let's set the image Height value to that we have on our original plan. Once you do this, you will see that the Resolution changed. This resolution is the very useful number. It says us that every measuring unit (inch) have N pixels on our image. And, as we haven't changed the pixels value, we can say that the previous reference image has the same N pixels per inch.

Copy that Resolution to clipboard.

Go to the previous reference square image and paste our new resolution. This time the resolution will change the Width and Height values. Do not forget to keep the Resample Image checkbox inactive.

Choose the measurement units to the right from the width or height, they must be the same as those you are using in 3d. Copy any of the sizes to clipboard. We can choose the Width or Height because we have square image, so they are equal.

It was a last thing in Photoshop :)

In 3ds max, create a plane and paste the obtained value to the plane sizes.

Apply the our square reference image to that plane.

Now we have the plan stretched over the 3d plane, where all dimensions correctly repeat the ones that are (and ones that missing) on the image plan.

If we check the inscripted  raster dimensions with any 3d tool, we can see that they match with the 3d ones.

That is all we needed! :)

Despite such a long description and the number of screengrabs, this method provides good accuracy.

It is good for understanding for those who knows Photoshop or any raster editor better than 3d software.

For much simpler method of doing the same thing in 3ds Max only, read the next post about matching 2d and 3d scale.