prism docs · Getting started · What do you want to map?

What do you want to map?

After a scan, prism shows the photo your phone took, outlines the objects it found and asks which ones you want to light. A click adds a thing or leaves it out. Everything you don't choose stays dark, unless you also map the walls and floor as a background.

WhereSetup ▸ Review, after every scan
Design ▸ Add ▸ Choose objects from the scan…

Clickadds a thing, or leaves an outlined one out

FinishMap 4 objects (Enter) · Skip (Esc)

ModeSimple all of it
Advanced Re-detect

1 · When it appears 2 · Reading the photo and the list 3 · Pick and unpick 4 · Parts and wholes 5 · Names 6 · Walls and floor as background 7 · Finish, or skip 8 · Choose again later 9 · Rescan Hints and tips When something looks wrong Mouse and keyboard

1When it appears

Right after a scan, when you click Review surfaces, the Review step opens with What do you want to map?. It appears once per scan. Nothing in your project changes until you finish, so you can try things freely.

Meanwhile the projector goes black and draws outlines on the real objects: white for the chosen ones, lime for the one under your pointer. Look up from the laptop to check you've got the right thing.

2Reading the photo and the list

The photo is the one the phone took. The parts the projector can't reach are veiled: nothing can be lit there.
Found objects are outlined with the shape they'll get and numbered left to right. Chosen ones are lime with a lime number; the others are dashed; ones the scan couldn't place well are amber.
The list on the right has the same numbers. Each row shows the object's picture, its name, its shape (Quad, Circle, Outline, or By hand) and why it is or isn't chosen: Suggested, Added by you, Small: not chosen, or Seems to lie on the floor: not chosen.
Above the list: how many objects are chosen, and the keys A (all suggested) and N (none).

Illustrated chooser with a lime selected plinth, unselected panel and amber weak box face — An explanatory diagram, not a real scan photograph. Inspect the proposed objects, leave unwanted areas unchosen, and correct weak or missing faces. Real results depend on your room and scan quality.

What do you want to map? with nothing chosen yet: the scan photo, the note that the scan didn't single out any objects, and the background switch — When the scan singles out nothing (as in this simulated room), the list says so and you click the things you want.

What prism suggests. Objects it placed well that aren't tiny and don't seem to lie on the floor. Flat pictures on a wall are never suggested by themselves: they're part of the wall until you click them.

3Pick and unpick

Hover over the photo. Over an outlined object, a label says what a click does: Remove: Column or Add: Column. Anywhere else, prism's object finder previews the region a click would add, filled, with Add this.
Click to add or leave out. The list and the projector's outlines follow at once.
Can't hit it? Drag a box around the thing.
Changed your mind? Ctrl + Z undoes the last change inside this step; the × on a row removes an object you added.

The pointer over a box face: its region is filled and labelled Add this — Hovering: the region a click would add, and “Add this”.

The projector drawing a lime outline around the hovered box face — On the projector at the same moment: a lime outline on the real object.

Four objects chosen, numbered 1 to 4 on the photo and in the list, with Map 4 objects — Four objects chosen. The footer counts them and Map 4 objects is ready.

The projector showing white outlines of the four chosen objects on black — What the projector shows meanwhile: the chosen objects in white on black, on the real objects.

4Parts and wholes

Things are made of parts: a speaker has a cone, a cabinet has doors, a box has faces. When you click, prism picks one size; you can step between them.

To…	Do this
Take a smaller or larger part	`Tab`, or `[` and `]`, or `Alt` + mouse wheel, on the object you last clicked.
Add a part to it	`Shift`-click the part.
Cut a part out of it	`Alt`-click (or right-click) the part.
Trace an outline yourself	`Alt` + drag along it.

Box faces. A box can be mapped as one object or face by face. Face by face gives each side its own look; one object is quicker. For boxes you place and align yourself, see 3D objects.

5Names

prism names objects by their shape: Disc (a circle), Column (three times taller than wide), Board (a big, wide rectangle), Panel (a four-sided shape), otherwise Object 1, Object 2… Numbers are added when a name repeats (Panel 2).

Click a name in the list to rename it, then press Enter. The surfaces keep these names in Design.

Renaming the first object in the list to Left box — Renaming an object in the list.

6Walls and floor as background

Also map the walls / floor as background decides what happens to everything you didn't choose.

Off (the default): only the objects light up; the rest stays dark.
On: the rest of the projection becomes background surfaces too, named Wall, Floor or Ceiling, kept together in a group called Background. The finish button then reads Map 4 objects and the background.

The background switch on: the background shown as a soft tint around the chosen objects — With the pointer on the switch, the background shows as a soft tint around your objects.

7Finish, or skip

Map 4 objects (or Enter; the number is how many you chose) makes exactly those surfaces, with their shapes (a quad, a true circle, a curved outline), and opens Design. Each new surface starts with the Test Grid look so it shows on the projector straight away. It is one undo step.
Skip (or Esc) keeps what the scan made by itself: the background as Wall and the objects it grouped.

When the scan couldn't place something. An amber row says “Scan data too poor here — rescan over HDMI, or place it by hand”. You can still choose it: it becomes a four-cornered surface to align on the projector by hand. Things the projector barely lit, like a shadow, aren't offered at all.

8Choose again later

You can come back at any time; the objects you keep keep their looks.

In Design: Add ▸ Choose objects from the scan…
In Setup ▸ Review: Choose objects to map…

Design's Add menu with Choose objects from the scan — Design ▸ Add ▸ Choose objects from the scan…

The chooser opened again from Design with the four mapped objects chosen — Reopened in Design: what the project maps is chosen. `Esc` closes it without changes.

9Rescan

Rescan goes back to the Scan step: do it when the projector or the objects moved, or when the scan was poor. Advanced Re-detect surfaces from this scan (under More… in Simple) finds the surfaces again from the saved scan, without scanning: each new surface keeps the name and look of the old one it covers.

Hints and tips

Look at the real objects, not only the laptop. The projector's outlines are the fastest check.
Fewer, bigger things first. You can always add more later from Design.
Leave the floor out unless you want light on it: projected light on a floor under objects is rarely pretty.
Name things now. “Speaker left” is easier to find than “Panel 3” once you have twenty surfaces.
Zoom the photo for small things: mouse wheel or pinch, and Space + drag to move around.

When something looks wrong

You see	Why	Fix
“The scan didn't single out any objects. Click one on the photo to map it.”	Nothing stood out clearly, or Geometry only detection was used.	Click the things you want; or rescan with the lights lower.
“Loading the detection model…”	The object finder is downloading for the first time (about 450 MB).	Wait; it's stored on this computer afterwards.
“Picking needs the detection model, which isn't available.”	The model couldn't be loaded (no internet on first use).	Choose among the outlined objects, or connect once so the model can download.
A click takes the wall behind the object too	prism picked a bigger part.	`Tab` or `[` for a smaller part; `Alt`-click to cut the wall out.
An amber object: “Scan data too poor here”	The scan read that area badly (common over Wi-Fi, or on shiny floors).	Rescan over HDMI, or choose it and align it by hand.
A thing at the edge of the photo can't be picked	It's outside the projector's picture (veiled).	Only what the projector lights can be mapped; aim the projector to include it and rescan.
The projector shows no outlines	The projector window isn't open or fullscreen.	Setup ▸ Outputs.

Mouse and keyboard

Action	How
Add or leave out	Click · drag a box around a thing
Smaller or larger part	`Tab` · `[` `]` · `Alt` + wheel
Add a part · cut one out	`Shift`-click · `Alt`-click or right-click
Trace an outline	`Alt` + drag
All suggested · none	`A` · `N`
Remove an added object	`Delete` · the × on its row
Zoom · move around	Mouse wheel or pinch · `Space` + drag
Undo · redo (inside the step)	`Ctrl` + `Z` · `Ctrl` + `Shift` + `Z`
Map them · skip	`Enter` · `Esc`

prism documentation · Getting started · screenshots taken in prism's simulator · 28 Sept 2026

What do you want to map?

1When it appears

2Reading the photo and the list

3Pick and unpick

4Parts and wholes

5Names

6Walls and floor as background

7Finish, or skip

8Choose again later

9Rescan

Hints and tips

When something looks wrong

Mouse and keyboard

Related