I've always wondered how to get this type of photos, taking random objects from my room for example (toys, furniture, etc.); and if people actually took HD dslr pictures of it a studio/white room before putting them on tshirts (removing white background I guess because one would just want the object and its shadow to create an illusion of 3D) or if some kind of flatbed scanners existed that could scan not just sheets but also more solid objects (see pictures: https://i.stack.imgur.com/GStQZ.jpg, https://i.stack.imgur.com/JZ809.jpg) :))
There exists few imaging methods which make 3D models of things. Some of them scan with laser or ordinary light rays. Method name "photogrammetry" sends nothing, it combines several photos taken from different directions without letting the object move between the shots. It can place also the shadow correctly.
In your case no special 3D equipment nor method is needed, only quite usual multilayer image composing work. Many of us do it daily. Others call it photoshopping.
The photo of the insect has been taken with a normal, but high quality camera. It's theoretically possible that its shadow was shot at the same time, but the light direction inconsistency suggests that it was made manually in a photo editing program.
The background of the insect is removed using normal practices. The clothing photo is in the bottom layer, in the middle there's the shadow and on the top there's the insect.
The shadow can well be the insect itself, only recolored to flat grey, geometrically distorted with warping and slightly blurred.
If one makes this with care, the bending of the cloth fabric will be taken into the account when the shadow is made. Here the problem has been cleverly removed by selecting the light direction separately for the longest legs. The maker surely has understood the problem. He seems for ex. to have taken the varying distance between the fabric and the insect into the account as well in the amount of the blurring as the placement of the shadow.
There are some signs of a hobby project:
- the direction of the light isn't the same for the cloth and for the insect
- the cloth seems to be fully undisturbed. A creature this big should stretch the fabric downwards. Alternatively the image should have been edited like the insect was printed onto the fabric.
I guess (not know) a couple of legs is a little stretched for artistic impact. I made a major restoration surgery for them:
Here's a screenshot from the shadow warping session. The shadow is a copy of the insect, only colored to single solid grey. It was blurred and made transparent after the warping: