3D tour glossary
The words that come up around walkable 3D tours, defined plainly. Each definition is written to stand on its own. Where a page on this site explains the term in context, it is linked.
- 360 photo (panorama)
A single image covering every direction from one point, captured by a 360 camera or stitched from several shots. A 360 tour is several of these linked by hotspots; the viewer can look around but not move between the captured points.
- Camera solve
Working out where the camera was, and which way it pointed, for each frame of a video. Produced by structure from motion. Without a solve there is nothing to train a splat against.
- Dollhouse view
A cut-away, top-down 3D rendering of a whole property that lets a viewer see every room at once, popularised by Matterport. VOLUME does not offer one today.
- Drift
Accumulated error in a camera solve over a long or featureless path, so that the end of a walk no longer lines up with the start. Hallways and stairs are where drift most often shows up in a tour as doubled walls or a tilted floor.
- Dwell time
How long a visitor actively spends inside a tour, measured from interaction rather than from the tab being open. VOLUME reports average dwell per tour to the owner without identifying the visitor.
- Embed
Placing content hosted on one site inside a page on another, most often with an iframe. A VOLUME tour embeds on any page that accepts an iframe; MLS listing forms generally accept only a URL.
- Equirectangular
The flat projection used to store a 360 photo or video, mapping the full sphere onto a 2:1 rectangle. Splat pipelines built for phone video do not accept it.
- Exposure lock
A camera setting that fixes brightness so it does not re-adjust as the scene changes. Locking exposure before a walkthrough stops the image pumping brighter and darker at every window and doorway, which helps reconstruction.
- Field of view (FOV)
The angular width of what a camera or viewer shows. A wider field of view shows more of a room at once and exaggerates depth; listing photos are often shot very wide, which is one reason rooms look larger in photos than in a walkable tour.
- Floor plan
A 2D drawing of a property's layout, usually with room dimensions. Produced by measured-capture systems such as iGUIDE or drawn separately; not derivable from a Gaussian splat without other tools.
- Gaussian splat
A 3D scene represented as millions of small, semi-transparent coloured ellipsoids (Gaussians) positioned in space so that, rendered from any viewpoint, they reproduce the photographed room. It is the format VOLUME tours are built in.
- Gaussian splatting
The technique of training a Gaussian splat from photographs or video frames with known camera positions, by adjusting each ellipsoid until the rendered views match the source images. Also refers to rendering such a scene.
- Hotspot
A clickable marker inside a 360 tour that jumps the viewer to another panorama or opens information. Walkable splat tours do not need navigation hotspots because the viewer moves freely.
- IDX (Internet Data Exchange)
The arrangement under which MLS listings are displayed on brokerage and agent websites. IDX rules are why tour links shown on other brokers' sites must not carry the listing agent's branding.
- iframe
An HTML element that displays another web page inside the current one. The standard way to embed a hosted tour; a single line of HTML that CMSs such as WordPress, Squarespace, and Webflow accept.
- Lead capture
A form inside or beside a tour where a visitor leaves contact details. On VOLUME the form sits in the tour page and submissions go to the owner's inbox and dashboard.
- LiDAR
A sensor that measures distance by timing pulses of light. Pro iPhones and some scanning cameras carry one. Useful for measured scans and meshes; not used by video-to-splat pipelines, which work from the colour frames alone.
- MLS (Multiple Listing Service)
A regional database of property listings shared among member brokerages and syndicated to public portals. Each MLS has its own listing form and its own rules for virtual tour links, usually requiring an unbranded link for public display.
- Motion blur
Smearing in a frame caused by the camera moving while the shutter is open. The most common reason a phone-video tour comes out soft; the fix is to walk and turn more slowly, and to add light so the shutter can be shorter.
- NeRF (Neural Radiance Field)
An earlier approach to the same problem as splatting: a neural network learns to return colour and density for any point and viewing direction in a scene. NeRFs render slowly compared with splats, which is why browser-based tours use splats.
- Parallax
The apparent shift of near objects relative to far ones when the viewpoint moves. Real parallax is what separates a walkable 3D tour from a 360 panorama, which has none because the viewpoint never moves.
- Photogrammetry
Measuring and modelling the real world from photographs. In 3D capture it usually means building a textured mesh from many overlapping photos; splatting is a related but distinct output.
- .ply (Polygon File Format)
A long-standing file format for 3D point and mesh data that splat pipelines adopted for storing Gaussians. Uncompressed, so files run tens to hundreds of megabytes for a home. VOLUME tours are downloadable as a splat file in this family.
- Point cloud
A set of points in 3D space, each with a position and often a colour, produced by scanners or by structure-from-motion. A splat can be thought of as a point cloud where each point has a size, orientation, and opacity.
- Poster frame
The still image shown in place of a tour or video before it loads or plays. VOLUME generates one per tour so a visitor sees the property immediately while the splat file downloads.
- Reconstruction
The whole pipeline from source video to finished 3D scene: frame extraction, camera solve, splat training, and export. On VOLUME a failed reconstruction is never charged.
- Spherical harmonics
A compact way of storing how a Gaussian's colour changes with viewing angle, so reflections and sheen look right as the viewer moves. Part of what makes a splat file larger than a plain point cloud.
- .spz
A compressed file format designed specifically for Gaussian splats. It quantises and compresses the per-Gaussian data to produce a file several times smaller than the equivalent .ply, which makes first load on a phone faster.
- Structure from Motion (SfM)
The process of recovering camera positions and a sparse 3D point set from a series of overlapping images by matching features between them. It is the first stage of every video-to-splat reconstruction and the stage that fails when footage is blurred or featureless.
- Turnaround
The time from upload to a live, embeddable tour. VOLUME's target is under an hour, stated as typical rather than guaranteed because reconstruction runs on a third-party pipeline.
- Unbranded tour
A version of a tour with no agent name, logo, contact details, or call to action, for use in MLS and IDX contexts. VOLUME issues one automatically for every tour alongside the branded URL.
- Walkthrough video
A single continuous video recorded while walking slowly through every room at head height. The only input a video-to-splat service needs; on VOLUME it must be 60 seconds to 5 minutes long and under 500 MB.
- WebGL
The browser graphics API that renders 3D content without a plugin. Splat viewers use it, which is why a tour opens in a phone browser with nothing to install.
Related
See the words in a real tour.
Your first tour is free, no card at signup. After that a single tour is $79. If a usable walkthrough can't be reconstructed, you're never charged.