Light, Shadow & a Touch of Magic
Surreal images can contain almost anything. But for the result to feel convincing, the different elements still need to belong to the same world.
Light is an important part of that. So are shadows, texture, sharpness, depth and scale. When these details agree with each other, even an impossible scene can feel believable.
In Tectonic Tortoise, for example, the challenge was not simply combining a tortoise with a landscape. The textures, light and depth of the different elements had to work together as one image.
I usually start with the main light direction and use it as a visual anchor. From there, shadows and highlights help connect the different parts of the composition.
Edges are equally important. Careful masking and subtle blending prevent objects from looking simply placed on top of each other.
Depth also plays a role. Sharpness, atmospheric perspective and depth of field help establish where an element sits within the scene.
None of these details are particularly noticeable when they work. That is the point.
The aim is not to make the technique visible, but to make the image feel natural enough for the viewer to accept the impossible.