Trompe l'oeil 2 : Process
Camera Matching Using fSpy :
With the photo and HDRI prepared, I moved to camera matching using fSpy. I imported the PC setup image into fSpy and aligned the perspective lines to match the geometry visible in the photograph. I focused on long straight edges such as the desk surface, the monitor frame, and any wall or shelf lines that helped define the vanishing points. Once I was satisfied, I exported the camera data and imported it into Blender, which gave me a camera that matches the photograph’s perspective.
This step was one of the most important parts of the workflow because if the camera match is even slightly incorrect, the 3D clock and pencil will appear to float or sit at the wrong angle, immediately breaking the illusion. After importing into Blender, I validated the match by placing a simple cube and plane into the scene to see whether the geometry aligned with the desk and other surfaces in the photo. This helped me confirm whether my scale and horizon line felt correct before I committed to placing the final objects.
Camera Projection Setup with a Ground Plane:
After confirming the camera match, I created a plane to represent the desk surface and used camera projection to help anchor the 3D objects into the photograph. I projected the photo onto simple geometry so that Blender would display the background plate from the correct perspective. This approach made it easier to judge contact points, scale, and positioning because I could see the 3D objects against the photographed surface in real time.
At this point, I focused on making sure the clock and pencil had believable contact with the surface. I adjusted their placement so they sat naturally on the desk plane, and I refined their rotation so they followed the same perspective cues as the rest of the scene. This stage was less about creating perfect assets and more about ensuring that the objects felt physically grounded in the image.
Adding the 3D Clock and Pencil into the Scene :
After setting up the camera match and camera projection, I moved on to adding the 3D clock and pencil into the scene. I either modelled these objects myself or used simple existing 3D assets that I adjusted to suit the scale and style of the photograph. Before focusing on materials, I concentrated on placement. Using the fSpy-matched camera as my active camera, I positioned the clock and pencil directly on the projected desk plane so that they aligned naturally with the perspective of the PC setup image. I carefully adjusted their scale by comparing them to familiar real-world objects already present in the photo, such as the keyboard, monitor stand, or desk edges. This helped ensure the objects did not appear oversized or unrealistically small.
Once the basic placement felt correct, I refined the rotation of each object so they followed the same visual logic as the photographed environment. The clock was oriented so its face was readable but still believable within the desk layout, while the pencil was rotated slightly to avoid looking perfectly aligned or staged. I learned during this stage that perfect alignment often looks artificial, so introducing small, natural-looking angles helped the objects feel more casually placed. I also checked that the objects intersected the plane correctly, making sure there were no visible gaps or floating effects at the contact points.
