Appendix D — Appendix D: Image Credits

Every image in this book belongs to one of exactly two categories, and the distinction determines both where the file lives in the book’s source tree and whether it appears in this appendix. The first category is hand-built SVG diagrams, stored under assets/images/diagrams/, used for anything conceptual or structural: coordinate frame conventions, ROS 2 node graphs, state machines, geofence polygons, control loops, and the labeled anatomy of motors, frames, and sensors. The second category is real photographs, stored under assets/images/photos/, used only where the subject is physical hardware and a photograph carries information a schematic cannot — the actual layout of components on a quadcopter frame, a bridge-inspection drone working beneath a real bridge deck, or the false-color output of a genuine multispectral field survey.

The reasoning behind the split is practical. A diagram of a body-fixed coordinate frame or a ROS 2 publish-subscribe topology needs axes, arrows, and labels that match the equations and code beside it exactly; hand-drawing that figure is faster and more accurate than searching for a stock image that happens to align with the text’s notation. A photograph, by contrast, grounds the reader in what the hardware actually looks like at real scale, with real wiring and real mounting hardware — detail a clean vector drawing would either omit or invent. Each kind of image does the job the other cannot.

The book also makes a deliberate editorial choice to use no AI-generated images of either kind. For a technical reference that a reader will study closely, accuracy and attribution matter more than production speed. A hand-built diagram can be checked, line by line, against the transformation matrices or node code it illustrates, and corrected when the text changes; a generated image offers no such audit trail, and its errors tend to be plausible-looking rather than obvious. Photographs are held to a parallel standard: every one is a real, verifiable image with a named author and an explicit license.

That policy explains why this appendix is short relative to how image-heavy the book actually is. The 71 hand-built diagrams spread across the chapters are original work created for this book and need no individual credit entries. Only the photographs require attribution, and there are five of them — all sourced from Wikimedia Commons, all licensed under CC BY or CC BY-SA. Their credits are maintained centrally in assets/images/photos/ATTRIBUTIONS.md and compiled automatically into the list below, so the entry here always matches the record kept alongside the image files themselves.

The following photographs are used under their stated licenses: