I had one afternoon to build a cutaway of Grand Central Madison for a short explainer about the LIRR terminal. I did not have CAD, survey data, or a modeling team. I had a browser and a rough question: can a map selection produce a base good enough to explain an underground station?
GenAnywhere turns a polygon drawn on a map into a generated 3D model. That is the workflow I tested.
The target
This was not an engineering model. I needed massing, levels, entrances, platforms, and track count. The station sits 140 feet below Park Avenue, with four platforms and eight tracks, and entrances spanning 44th to 48th Streets. For a cutaway, the relationships matter more than the details.
Step 1: pick the right selection
My first box was too tight: the terminal footprint only. The result had no street context, and the ground plane ended in midair. The second selection covered Grand Central Terminal, the street grid from 42nd to 50th, and a block on either side of Madison. That gave the model enough context to read as a place.
Step 2: audit everything the model claims
Generated models look confident. Check them anyway. I counted four platforms and eight tracks. I measured the depth from the street to the concourse against the known 140 feet. I checked that the entrances fell between 44th and 48th. One escalator bank was missing, and the terminal above was simplified into a single mass. I logged both.
Step 3: cut it open
A cutaway needs a clean section, not a hole. I clipped the model along a plane through the concourse, removed the near half of the city, and capped the exposed ground with a solid layer. The section wall got a darker material so the eye reads it as a cut. This is the step where a generated model starts to look intentional.
Step 4: rebuild the circulation
The escalators do most of the work in this station. There are 47 escalators and 22 elevators, and they connect street, concourse, and platforms. The generated base had a few ramps where the main banks should be. I replaced them with simplified escalator runs at the correct angles and added the major elevator cores. I did not model every unit; I modeled the paths a passenger would recognize.
Step 5: light it and place cameras
Three cameras did most of the work: one at street level looking into the entrance, one at the concourse floor looking across the hall, and one on a platform looking down the track. I lit for readability, not realism. The concourse is bright and even, so a soft overhead source plus bounce was enough. The tunnels needed a darker falloff to keep the cutaway from looking flat.
Step 6: add what generation cannot
The base model does not know how the station was built. For a second scene, I built a tunnel boring machine and a ventilation level separately. The TBM scene is a construction view; the equipment level is a service view. Both are useful for explaining the station, and both needed to be modeled by hand.
Where it holds up
The generated base is good at massing and context. It gave me the street grid, the terminal above, and a rough underground volume in a single pass. For a cutaway that has to read in five seconds, that is most of the battle.
Where it fails
The model is not suitable for clearance checks, structural analysis, or construction planning. Track alignment is approximate. Ventilation shafts and cross passages are missing or simplified. The ceiling and finishes are placeholders. If the deliverable needs to be measured, this is the wrong starting point.
What I would change
I would split the selection: one model for the station and immediate streets, one for the wider Midtown context. I would also do the cutaway before adding any detail, because clipping a detailed model wastes time on geometry that will be hidden.
The time split was lopsided. Selection and generation took under ten minutes. Cleanup took most of the afternoon, and most of that was deciding what to leave out rather than modeling. The cutaway reads better when you remove more than you add.
Verdict
For an explainer, a map-generated base plus an afternoon of cleanup got me a cutaway I could light and hand off. It is a blockout tool, not a survey tool. Treat it that way and it earns its place in the pipeline.
