A perspective projection can be precisely specified through four pairs of corresponding points. By dragging the four corners of the grid above, you can adjust the perspective projection interactively and place the grid anywhere you like in the scene. The grid lines are transformed using a matrix computed by solving linear equations from the four point-pairs via LU decomposition (numeric.js). D3 handles the SVG rendering and animation, with draggable corner handles and preset scene buttons (Floor, Near Wall, Far Wall, Reset) for quick placement.