How previews are generated

Updated Sep 3, 2026 · 5 min read

Previews render as you browse by default, or all upfront after each scan if you prefer, and a card can show the picture that came with the model instead of Meshory's render.

By default, Meshory doesn't render your library up front. Previews are demand-driven: the grid asks for the models currently onscreen, plus your favorites, and a pool of background workers renders those. Scroll on and the queue follows you. On a terabyte-scale library that's the difference between an app you can browse in minutes and one that renders for hours before it's useful to you.

Each preview arrives in two stages. A draft is rendered first from a sampled read of the mesh, so a tile stops being blank almost immediately, then a full-quality render replaces it. A 3MF that carries a slicer's own embedded preview uses that image directly. The sidebar shows Processing thumbnails while drafts are being made, and Refining previews while they're being upgraded. Neither is a rescan of your source.

The pool sizes itself to your machine (one worker per CPU core, keeping one core free so the app and your system stay responsive), spins workers up only when there's rendering to do, and winds them back down once they've been idle. Memory is sized to your machine too: very mesh-dense files are processed a couple at a time within strict memory bounds, so a folder of 100 MB models can't blow past your RAM no matter how many cores you have. There's nothing to tune.

What a card shows: Preview pictures

A 3MF downloaded from MakerWorld usually carries the model's cover photo inside the file. Preview pictures, in Settings → Scanning, decides whether a card shows that cover or Meshory's own render. Original pictures uses the cover saved inside the file. Without one, it uses a photo with exactly the same name next to the file, like Arm.jpg beside Arm.stl, and otherwise the render. No other photo from the model's folder is used, since it often shows a different model. 3D previews always uses the render, so every card has the same angle and lighting.

Folder cards follow the same setting. With Original pictures, a folder that holds a photo shows that one photo instead of a grid of parts, preferring a photo named after the folder over the rest. A photo sitting in the folder itself comes before one in a subfolder like Images, and a folder full of kits shows one photo from each of the first four. Photos packed inside an archive are used only when there's no other photo. A folder without photos, or any folder under 3D previews, shows the models inside it.

To choose a folder's picture yourself, right-click the folder and pick Change cover…. Any photo or model inside it can be the cover, including ones in subfolders, or pick Upload image… to use a picture from anywhere on your computer. You can also right-click a photo and pick Use as folder cover, which offers the folder it sits in and every folder above it. A cover stays on the card under either setting, and under Original pictures a parent folder's card also uses it for that subfolder. Choose Automatic, or pick a ticked folder again, to go back to Meshory's pick.

The shipped default is 3D previews, and updating doesn't change it: an existing library keeps its renders until you switch. The setup wizard asks new installs which they want. Switching re-creates previews for the files it affects, cards on screen first and the rest as they come into view. A folder's photos also show up in the Change thumbnail picker, under their own Folder photos heading, so a pack that ships with renders can use one without you hunting for the file.

When rendering happens: Preview generation

Preview generation, in the same settings section, decides when the work happens. As you browse is the demand-driven mode described above: light on the drive, nothing running in the background, and the right answer for a NAS. All upfront renders every new model after each scan instead, so no card is a placeholder by the time you reach it. On a big library that takes hours and keeps the source drive busy, which is why the setting confirms before it starts, and why the sidebar lets you pause or stop the run.

In either mode you can ask for the work directly. Generate thumbnails, in a source's ⋯ menu, checks every indexed thumbnail in that source and regenerates any that are missing; the sidebar shows progress per source while it runs, and you can pause, resume or stop it at any time.

Pausing work on a source

Each source row in the sidebar carries its own controls. Pause preview generation to stop rendering for that source while leaving the rest of your library alone, or pause tag generation to stop the automatic tag and metadata pass on its own. The tag-generation pause is remembered across launches; the preview pause lasts for the session. Stopping a source's processing stops both, including preview work that used to keep running after a scan was stopped.

Skipping folders you don't want scanned

The scanning knob that does exist: the Scanning section in Settings takes a list of excluded names, so folders or files matching those patterns are left out of scans entirely, handy for backup dumps or work-in-progress folders you don't want in the library. See What Meshory indexes for the full picture: supported formats, folder exclusions, and index-only patterns.