How to Invert Heightmaps for Concave vs Convex 3D Prints

When converting 2D images into 3D models using heightmaps, one setting has a more dramatic impact on your final physical print than any other: Invert Heightmap (Invert Z). Getting this setting wrong turns raised text into sunken trenches, embosses photo shadows as mountain peaks, or turns a clean 3D stamp into a mirror relief.

In this guide, we break down how heightmap Z-axis elevation is calculated, when you should invert your heightmaps, and how to preview your model in your slicer before sending G-code to your 3D printer.

Understanding the Heightmap Pixel-to-Z Math

Heightmap conversion algorithms evaluate image pixel brightness on a scale from 0 (pure black #000000) to 255 (pure white #FFFFFF). In default (non-inverted) mode, white pixels represent maximum Z-height elevation (raised geometry), gray pixels represent mid-level Z-height, and black pixels represent floor base level (0 elevation).

However, most logos, drawings, and signatures are drawn as black ink on white paper! If you convert a black logo without inverting, the background paper turns into a tall 3D wall while your logo ink becomes hollow cutouts!

When to Invert vs Non-Invert Matrix

Previewing Z-Elevation Polarity in Slicers

Always rotate your model in your slicer to inspect the underside. A correct raised logo will feature a completely solid bottom base plate with text protruding upward. If text is carved downwards into the base, return to ImageToSTL and toggle the Invert Heightmap switch!

Hardware Compatibility & Calibration Checklist

Achieving pristine surface quality and tight dimensional tolerances requires a well-maintained 3D printer frame. Check that your X and Y axis belts are tensioned to approximately 110 Hz – 120 Hz, verify that your Z-axis lead screws or belt drives are free of debris, and perform a PID tune on your hotend heater block to eliminate temperature oscillations that cause subtle horizontal banding on outer model perimeters.

Step-by-Step Slicer Profile Optimization

Before launching your final print job, review your sliced G-code preview in OrcaSlicer, Bambu Studio, or PrusaSlicer. Use the color-coded speed legend to inspect wall velocities—keeping outer wall speed constant across the entire part height ensures uniform surface gloss. Verify that seam placement is aligned to sharp rear corners or hidden inside inset geometry to preserve a smooth front face.

Hardware Compatibility & Calibration Checklist

Achieving pristine surface quality and tight dimensional tolerances requires a well-maintained 3D printer frame. Check that your X and Y axis belts are tensioned to approximately 110 Hz – 120 Hz, verify that your Z-axis lead screws or belt drives are free of debris, and perform a PID tune on your hotend heater block to eliminate temperature oscillations that cause subtle horizontal banding on outer model perimeters.

Step-by-Step Slicer Profile Optimization

Before launching your final print job, review your sliced G-code preview in OrcaSlicer, Bambu Studio, or PrusaSlicer. Use the color-coded speed legend to inspect wall velocities—keeping outer wall speed constant across the entire part height ensures uniform surface gloss. Verify that seam placement is aligned to sharp rear corners or hidden inside inset geometry to preserve a smooth front face.

Hardware Compatibility & Calibration Checklist

Achieving pristine surface quality and tight dimensional tolerances requires a well-maintained 3D printer frame. Check that your X and Y axis belts are tensioned to approximately 110 Hz – 120 Hz, verify that your Z-axis lead screws or belt drives are free of debris, and perform a PID tune on your hotend heater block to eliminate temperature oscillations that cause subtle horizontal banding on outer model perimeters.

Step-by-Step Slicer Profile Optimization

Before launching your final print job, review your sliced G-code preview in OrcaSlicer, Bambu Studio, or PrusaSlicer. Use the color-coded speed legend to inspect wall velocities—keeping outer wall speed constant across the entire part height ensures uniform surface gloss. Verify that seam placement is aligned to sharp rear corners or hidden inside inset geometry to preserve a smooth front face.