Store Window Projection Mapping: The Under-$500 Setup, Including the Software Step Nobody Names

Why Rear Projection Wins for Store Windows

You could stand a projector on the street and throw the image at the window from outside. Nobody who has tried it does it twice. The beam crosses the sidewalk, so every passer-by becomes a two-metre silhouette sliding across your display, and the projector itself spends the evening outdoors collecting rain, kicks and attention from people who resell projectors.

Rear projection turns the whole problem around. The projector sits inside the shop — dry, powered from a normal socket, locked in with the stock — and fires through the glass from behind. Nobody can block the beam, because nobody is between the lens and the window. The street sees a bright image floating in the glass with no visible hardware, which is most of why those smart-glass quotes run to five figures: the effect reads as expensive even when it is not.

One piece of physics makes it work: clear glass does not hold an image. Light needs something to scatter on, and plain glazing lets the beam sail through and land dimly on the buildings opposite. Rear-projection film is that scattering layer — a translucent sheet applied to the inside of the glass that catches the image and turns the pane into a screen. The film is the difference between a window display and an expensive flashlight aimed at the street, which is why it is the first line of every vendor's parts list and why the quality of that film decides how the display survives ambient light.

The Parts List, With Honest Prices

Rear-projection film: $30–100

Two decisions. First, static-cling versus adhesive. Static-cling film grips the glass electrostatically, peels off clean, and survives being taken down in January and rehung in October — the right call for seasonal windows, and the cheaper one at roughly $30–60 for a window-sized sheet. Adhesive film is optically flatter and cleaner, with no risk of the sheet sagging off the glass in a heatwave, but application is a one-shot job with a squeegee and soapy water, and a trapped bubble is trapped forever. Expect $40–100 depending on size and grade.

Second, and more important: grey film beats white film for retail. A bright white film looks better in the stockroom demo, but a shop window lives with streetlights, headlights and your own interior spill, and every bit of that ambient light lifts the film's black level. A grey or dark-tinted film sacrifices a little peak brightness to hold contrast in exactly that environment — this is what "daylight film" and "high-contrast film" listings are selling. For a window that runs at dusk and after, grey is the default, not the upgrade.

A projector with real ANSI lumens: $250–400

For evening retail, plan on 3,000 ANSI lumens or more. A typical window of two or three square metres, on grey film, against streetlight, sits comfortably in the 3,000–5,000 ANSI band — a smaller target than the 3,500–6,000+ ANSI we recommend for a whole house facade, because you are lighting a fraction of the area. The trap is the spec sheet: boxes advertise "LED lumens" or "light source lumens" that run about ten times the ANSI figure, so a $90 projector shouting 12,000 lumens is delivering nearer 1,200 ANSI and will look like a rumour through film. Read only ANSI numbers (the FAQ defines ANSI lumens and throw ratio if the terms are new), and buy from the established business-projector brands, where a genuine 3,000–4,000 ANSI 1080p unit runs $250–400 new and less refurbished. Our full guide to choosing a projector for projection mapping walks the whole decision.

And be honest with yourself about daylight. No projector in this price class — or several above it — beats direct sun on a south-facing window. Window projection is an after-dusk medium. Run it from late afternoon in winter, from evening in summer, and let the glass be a normal window while the sun is on it.

Mounting, throw and the hotspot: $20–40

The projector needs clear depth behind the glass: image width times throw ratio. A 1.5 m wide window from a standard 1.2:1 lens needs about 1.8 m of empty space behind the film, which many window bays simply do not have — that is why short-throw models in the 0.5–0.8:1 range get specified for this job, covering the same glass from under a metre.

Do not mount the lens dead-centre at eye height. Rear projection has a failure mode front projection does not: stand in line with the lens and you see a bright hotspot of the lamp burning through the middle of the film. The fix is geometry — mount the projector high on a $20–40 ceiling bracket or a shelf above the bay, angled down, so the hotspot aims at the pavement rather than at eyes. That off-axis angle skews the image into a trapezoid, which is precisely the distortion the software step corrects. Skip the projector's own keystone correction; it burns pixels doing badly what mapping does properly.

Add a media stick for playback ($30–50, or an HDMI cable to a computer you already own) and the tally for a 1.5 m window is roughly: film $60, projector $350, mount $30, playback $40 — about $480 before SurfaBeam Pro, which includes a one-time purchase option rather than another subscription on the books.

The Software Step Every Vendor Page Skips

Here is what "a PC running signage software" hand-waves past: signage software plays files, it does not fit them to glass. Your projector hangs high and off-axis, so the image arrives as a trapezoid. The window is taller than 16:9, or wider, or has a transom bar across the top third. The film stops 5 cm inside the frame. None of that is a playback problem — it is a mapping problem, and it needs solving exactly once. In SurfaBeam you corner-pin a surface to the film, mask off everything that is not film, and warp the edges until the image agrees with the real glass. Budget an hour the first evening. Here is the sequence.

Step 1: Hang the film and place the projector inside

Clean the glass properly, then apply the film to the inside face of the window, cut about 5 cm inside the visible glass on every side — a border of clear glass around the image reads as deliberate, and it keeps the film's edge off the frame where dust collects. Then place the projector behind it: clear depth equals image width times throw ratio, so a 1.5 m wide image from a 1.2:1 lens needs about 1.8 m behind the glass, and a shallow window bay is exactly why short-throw lenses get specified for this job.

Step 2: Flip the output for rear projection

Walk outside and look: everything is mirrored, and any text is backwards. Open the projector's own menu and set the projection mode to Rear, or Rear/Ceiling if it hangs upside down from a mount. Every projector has this setting, it flips the image horizontally at the hardware level, and doing it now means everything you map from here on already reads correctly from the street.

Step 3: Map a surface to the glass

In SurfaBeam, tap Add Surface and drag the surface's four corner dots until they sit on the four corners of the film, judged from the sidewalk rather than from behind the projector. Everything outside a surface stays black, so the frame, the wall and the ceiling of the window bay go dark the moment the corners land.

This is the step that separates a mapped window from a projector pointed at one. The dark border around the film is what makes the image look like it belongs to the glass instead of being sprayed across the architecture.

Step 4: Mask to the frame and the glass you cannot use

If the window is a plain rectangle, the four corners from step 3 are the mask and you are done. If it is not — an arched top, a transom bar across the glass, vinyl lettering you have to dodge — tap Pick Custom Mask and hand SurfaBeam a black-and-white PNG of the shape you want lit: white where the image should land, black where it should not. Slide Threshold until the cut sits exactly on the edge, and use Invert if the app keeps the wrong side.

Getting that PNG is easier than it sounds: photograph the lit window from the street, crush the photo to pure black and white on your phone, and the silhouette matches the real glass from the one viewpoint that matters.

Step 5: Warp the edges the glass disagrees with

Stand where customers stand and look for lines that should be straight but are not — an off-axis projector bows them, and a century-old shopfront was never square to begin with. Select the surface, toggle WARP, then double-tap a corner to reveal its two orange tangent handles and pull the nearest edge until it runs parallel with the real frame. Repeat corner by corner. Four corners and their handles are the whole system; there is no grid to manage.

Step 6: Judge it from across the street

Cross the road and look back the way a passer-by will. Check three things: no hotspot burning through the middle of the film (raise or angle the projector if there is), no spill on the frame or the bay ceiling (mask it), and blacks that read as glass rather than grey (kill the window bay's own lights and drop the projector out of its showroom picture mode).

Doing this pass from a phone or tablet standing on the sidewalk, with the mapping controls in your hand, is the single best argument for a touch-native tool: you see the error and fix it without walking back inside.

The Runtime Decision: Export a File or Run It Live

Once the window is mapped, you choose how it runs every night, and this is where the under-$500 story either holds or quietly grows a dedicated PC.

Path one: export and loop. For an unattended shop window playing the same content on repeat, use Pro's Export to render your clip with the mapping baked in — the corner pinning, the mask, the warp, all burned into the pixels of an ordinary video file. That file plays on anything: a $40 media stick behind the projector, the projector's own USB media player, a spare tablet, whatever. Set it to loop, and the machine that runs your window every night needs no mapping software, no login and no attention. This is the most robust way to run a window nobody is standing next to — there is nothing to sleep, update itself, or pop a notification over your display at 8pm.

Path two: run it live. Keep the Windows or macOS build driving the projector when you want the Timeline — sequencing several clips through the evening, changing content without re-exporting, or using the effects and visualizer tools in real time. It costs you a computer that stays on and awake (disable sleep before you lock up; a screensaver over a shop window is a classic), and it earns you flexibility the baked file cannot offer. Most single-window shops start on path one and move to path two when the display becomes part of how they merchandise.

If you author on a tablet at the glass and host on a PC, note there is no cloud sync and nothing moves by itself: Pro's Save to Files writes a portable Scene_<date>.json that Load from Files opens on the other machine, but the project stores links to your media, so carry the clips across too or they come back missing. The simplest route remains authoring on the machine that will host.

And the plain statement this page owes you: the free version is not the tool for a live customer-facing window. SurfaBeam's free tier is permanently free, not a trial, and it includes the complete mapping, masking and warping toolset plus an entry gate before mapping (subscribe, or watch a rewarded ad on Android) — ideal for rehearsing the whole window before spending anything. But it watermarks both the projected output and any export, and a watermark over your shopfront defeats the point, while Save, Load and Export are Pro-only anyway. Pro is sold monthly, quarterly, yearly or as a one-time Lifetime purchase on the App Store and Google Play; on Steam it is a one-time DLC, not a subscription; and the direct Windows build sells its own Personal and Commercial licences.

Seasonal Windows Are the Gateway

Most shops do not start with a year-round display. They start with October, because a projected window at Halloween out-draws a static one for the price of a film sheet, and the same rig comes straight back out in December wearing snow. The retail calendar is the business case: one projector, one film, one mapped window, re-dressed four or five times a year with new content while the mapping stays identical.

The content side of those two seasons is already written up: our guide to DIY Halloween and Christmas projection covers what to play and where to find loops, and if the window season goes well enough that the whole building is next, house projection mapping for Christmas scales the same mapping skills up to a facade. The window is where you learn the tool with a two-metre target and a power socket within reach.

Frequently Asked Questions

What film do I need for a storefront window projection?

Rear-projection film, applied to the inside of the glass — clear glass alone will not hold an image, because the light needs something to scatter on. Static-cling film is repositionable and survives being taken down and reused, which suits seasonal windows; adhesive film is optically cleaner and flatter but is a one-shot application. For a window that has to fight streetlight and interior spill, choose a grey or dark-tinted film over a bright white one: the grey base holds black level and contrast in ambient light that washes a white film out.

How bright does the projector need to be for a store window display?

For evening retail, plan on 3,000 ANSI lumens or more, and read every spec sheet in ANSI lumens only — boxes advertising "LED lumens" inflate the number roughly ten times, so a 9,000 LED-lumen listing is a 900 ANSI projector that will disappoint through film. A typical shop window of two or three square metres sits comfortably in the 3,000 to 5,000 ANSI band once street and interior light are managed; full daylight is a losing battle for any projector, which is why window projection earns its keep after dusk.

Can I run a shop window display on the free version of SurfaBeam?

You can build and rehearse the whole window on the free version, which has the complete mapping, masking and warping toolset and is permanently free rather than a trial. But the free tier watermarks both the projected image and any exported video, and a watermark over your own shopfront is not the look you are paying a window to create. It also cannot Save, Load or Export, so the alignment cannot be kept or baked into a file. For a customer-facing window, Pro is the tool.

Do I need a PC running signage software to keep the display going?

No — and this is the step the film vendors never explain. Author the window once in SurfaBeam, then either export the warped, masked result to a video file with Pro and loop that file on any cheap media stick or the projector's own USB player, or run the Windows or macOS build live when you want the Timeline sequencing clips through the evening. The export path means the machine that plays the loop needs no mapping software at all.

Why is the image mirrored, and where do I fix it?

Because you are projecting through the glass from behind, the street sees the image reversed. Fix it in the projector, not in your content: every projector has a Rear projection mode in its setup menu that flips the output horizontally, plus Rear/Ceiling for upside-down mounting. Set it before you start mapping and every clip you ever play — and everything you map in SurfaBeam — reads correctly from the sidewalk.

More definitions and store-agnostic answers live in the SurfaBeam FAQ, and the user guide documents every panel and gesture in the app.

Map it on a quiet Tuesday, not the night before the season

Hang the film, mount the projector, and do the map-mask-warp pass once after closing with the lights off and nobody waiting. Then export the loop with Pro and let a $40 stick do the night shift. Install SurfaBeam from the download page on the machine that will host the window — the toolset is the same on Windows, macOS, iOS and Android.

Windows (.exe) macOS, iOS & iPadOS Windows (Microsoft Store) Windows (Steam) Android — Pro Android — Free