Dragon engraving at 200 mm wide: a very dense drawing, and still a workable file. The table above uses this image at 100 mm.
Download example SVG (141 kB)Download example DXF (1.0 MB)
Source image: Openclipart, Darkmoon-Art, CC0 1.0.
Too many nodes in LightBurn: why it happens and how to fix it
A heavy, laggy file in LightBurn is usually a bad trace. Here is what causes it and how to get a clean vector with far fewer nodes.
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Real examples, made with this converter
Each pair is an actual conversion of a public domain image, with the settings listed under it. You can download the exact files.
Dot mandala: hundreds of small circles, each a separate closed contour.
Download example SVG (60 kB)Download example DXF (466 kB)
Source image: Openclipart, DG-RA, CC0 1.0.
Round lace frame: a fine ornamental pattern with hundreds of small closed shapes.
Download example SVG (75 kB)Download example DXF (786 kB)
Source image: Openclipart, GDJ, CC0 1.0.
Free sample files, not watermarked.
Recommended settings
To keep the node count low, change these before you convert.
- Profile
- Laser / CNC.
- Colors
- 1. Every extra color adds duplicate edges.
- Detail
- Medium, or low for the fewest nodes. Features smaller than the detail value are dropped.
- File to import
- The SVG if you want the fewest nodes. The DXF has more points because it stores curves as segments.
Symptoms
- The canvas redraws slowly and moving or selecting shapes lags.
- The node tool is unusable because a single outline has thousands of points.
- The saved G-code is huge, and the machine stutters or pauses along curves.
Why it happens
A bitmap is a grid of pixels. A basic auto-trace follows the grid and puts a node at almost every pixel step, so a smooth circle becomes a staircase of hundreds of points. DXF files made by converting rasters are the worst case: every vertex is a straight segment.
A clean vector works the other way. It finds the corners, then fits a few Bézier curves between them within a tolerance. This converter uses a tolerance of 0.05 mm, and details smaller than the detail option are removed instead of traced.
Same image, three detail settings
The image "dragon engraving" at 100 mm wide, converted three times with the laser profile, changing only the detail option. The counts come from the real results. The last row is a reference: the boundary points of the original bitmap, which is what a trace that follows the pixels would place as nodes.
| Detail | Contours | Nodes (SVG curves) | Vertices (DXF polylines) |
|---|---|---|---|
| Low (drops features under 1 mm) | 157 | 3,072 | 17,010 |
| Medium (0.5 mm) | 264 | 3,461 | 19,097 |
| High (0.25 mm) | 407 | 3,812 | 20,837 |
| Reference: one node per pixel step of the 512 px bitmap | – | 21,766 | – |
The SVG keeps curves, so it needs far fewer nodes. The DXF stores every curve as small straight segments (within 0.01 mm), so LightBurn shows more points when it opens the DXF.
Fix a file you already have in LightBurn
- Select the shapes and use Optimize Selected Shapes to reduce nodes within a tolerance.
- Run the duplicate-shape cleanup if the design has overlapping lines.
- If the file came from a raster, trace again from the source image instead of repairing it.
Check your node count in LightBurn
LightBurn SVG preferred
- Import the SVG. Select a shape and press N for the node tool to see its points.
- Import the DXF to compare: the same design has more vertices.
- Check the file size of the exported G-code in the Save GCode dialog.
Common mistakes
- Importing a DXF when the SVG would do. LightBurn gets curves from the SVG and short segments from the DXF.
- Tracing at a very high detail. More detail means more nodes. A laser cannot cut a 0.1 mm feature anyway.
- Tracing a photo. Every tonal change becomes an edge. Use a drawing.
- Using several colors to cut. Duplicate edges double the work and the nodes.
Questions
How many nodes is too many?
There is no fixed limit. If the canvas lags or the G-code is huge, you have too many. A simple logo should have a few hundred at most.
Do fewer nodes mean a worse shape?
Not if they are fitted well: a curve described by 4 control points is exact. It becomes worse only if the tolerance is too wide.
Does the converter tell me the node count?
Yes. The preview shows the number of paths and nodes before you pay.