Turn alpha masks or dark image contours into STL cutouts. Tune threshold, retain holes and filter small islands before inspecting the closed model.
A transparent alpha mask or dark brightness threshold becomes a solid cutout. Internal holes and separate islands are preserved. JPG has no transparent background.
A real conversion made with this tool. Your model will appear here after generation.
Example size: 100.0 × 158.8 × 4.0 mm
Choose an image → Set size → Generate → Download STL
STL coordinates are in mm. No colors or textures. Review walls and orientation in your slicer before printing.
Original inputs, actual generated meshes and downloadable STL files. These are digital previews, not photographs of printed objects.
At threshold 0.35, only the darker rectangle is foreground. Raising the threshold can include the lighter independent rectangle.
Width (mm): 100 · Resolution: 128 · Extrusion thickness (mm): 4 · Threshold: 0.35 · Minimum island area (grid pixels): 8
100.00 × 158.82 × 4.00 mm · 12 triangles · 1 closed shell
Internal holes and a separate island are retained. Independent shells need separate placement or a prepared connection before printing.
Width (mm): 100 · Resolution: 128 · Extrusion thickness (mm): 4 · Threshold: 0.45 · Minimum island area (grid pixels): 8
100.00 × 102.75 × 4.00 mm · 64 triangles · 2 closed shells
An opaque silhouette has no alpha channel to separate its background. This mode selects dark pixels below a brightness threshold, traces the resulting contours, identifies holes and independent regions, and gives each valid outline a constant extrusion thickness. If a source includes transparency, alpha takes priority instead. Choose a dark-on-light source when you want the threshold control to determine the foreground.
The two-tone rectangle sample makes threshold behavior easy to see. At 0.35 only the darker rectangle is selected; at 0.7 the lighter independent rectangle is also included. The full foreground bounds are fitted to Width, so adding another region can change the physical size of the first region even though the Width value stays at 100 mm. The letter-like second source tests two internal holes and a separate island rather than a single solid blob.
Minimum island area removes small connected foreground regions in sampled grid pixels. It does not enforce a physical wall thickness, connect separate pieces or repair a shape touching only at a point. Smoothing changes the raster outline and can remove fine detail. If the result contains unwanted islands, clean the original image and compare the preview with your intended design before exporting. Rejection of unreliable contour topology is preferable to an apparently successful download containing an invalid solid.
| Control | Starting point | What to inspect |
|---|---|---|
| Threshold | 0.45 initially | Opaque dark pixels below the threshold become foreground. The controlled sample compares 0.35 and 0.7; this control does not replace alpha for a transparent source. |
| Width / thickness | 100 mm / 4 mm | Width fits the whole selected foreground, including distant islands. Thickness sets a constant Z depth independently of the outline. |
| Minimum island area | 8 grid pixels | Filters tiny components in the sampled mask. It is not eight square millimeters and is not a minimum wall-width guarantee. |
| Resolution / smoothing | 256 / 0 initially | Grid density and smoothing influence edge details. The examples use grid 128 and expose the selected islands explicitly. |
The same opaque image changes from one closed shell to two. The foreground bounding box is fitted to Width, so each individual rectangle can change size. Both files use the same input and recorded settings; the single change is shown below.
| Recorded STL result | Baseline | One parameter changed |
|---|---|---|
| Bounds | 100.00 × 158.82 × 4.00 mm | 100.00 × 51.92 × 4.00 mm |
| Triangles / shells | 12 / 1 | 24 / 2 |
| Volume | 63529.4 mm³ | 14578.4 mm³ |
| Download for inspection | Baseline STL | Comparison STL |
Closed geometry and dimensions were checked after download. These measurements describe these files; they are not a printability guarantee.
STL stores triangles without units, colors or textures. This tool writes coordinates intended as millimeters. Closed-mesh validation checks finite coordinates, oriented shared edges and positive volume; it does not certify your printer, material or every thin feature.
JavaScript and Web Workers are needed for conversion. WebGL enables the interactive preview; if preview initialization fails, an already validated STL can still be downloaded.
The V1 baseline fixture silhouette-letter-b-island produced actual layered G-code in both slicers. Across the four modes, eight baseline STL files were checked in Bambu Studio and PrusaSlicer. Their recorded files and hashes are retained.
These are baseline slicing checks, not tests of every gallery parameter variation or physical print. Open your own downloaded model, check dimensions and thin features, and choose settings for your printer.
Recorded baseline results
It removes connected foreground islands smaller than that number of sampled grid pixels. It is not a physical minimum wall thickness setting.
Two regions touching only at a corner can create a non-manifold or fragile solid. Add a real connecting bridge or separate them in the source image.
More foreground can expand the overall selected bounding box. The converter fits that whole outline to Width, so the relative size of individual components can change. Check the final model rather than comparing only the control value.
No. Separate valid shells remain independent. Add a real connecting bridge or prepare a backing design yourself if you want one assembled printable part.
Files stay on your device. Desktop: up to 20 MB / 8 million pixels. Touch phones: 10 MB / 4 million pixels. SVG: 1 MB with bounded complexity. PNG, JPG, WebP and prepared SVG only. Use original or permitted artwork; model conversion does not grant image or trademark rights.
