# GMT topo

Canonical URL: https://colorcurio.us/colormaps/ncar.GMT_topo
Source type: Colormap
Type: sequential
Collection: ncar
Attribution: NCL/NCAR — UCAR (via hhuangwx/cmaps MIT wrapper)
License: MIT (wrapper) / public-domain (data)
Source: https://raw.githubusercontent.com/hhuangwx/cmaps/master/cmaps/colormaps/ncar_ncl/GMT_topo.rgb
Tags: cartographic, terrain, land-and-sea
Stops: 256

## Summary

GMT topo is a sequential colormap from the ncar collection. Inspect its perceptual lightness, chroma, and hue profile on colorcurio.us.

NCL GMT_topo bathymetry+topography in one ramp.

## Perceptual profile (OKLCh)

- Lightness: 0.684 → 1.000 (range 0.393, min 0.607, max 1.000); non-monotonic; midpoint 0.733
- Chroma: min 0.000, max 0.176, mean 0.081
- Hue: 6.3° → 17.5° (span 360.0°), path monotonic-ccw; quadrants: red, rose, magenta, violet, blue, azure, cyan, mint, green, chartreuse, yellow, orange
- Endpoint temperature: warm → null
- Perceptual ΔE: total 305.9, mean/step 1.200, max step 27.514, smoothness 0.000, speed 1.000

## Colorblind safety (ΔE under simulated CVD)

- Protanopia: ΔE total 235.1; preserves order: no
- Deuteranopia: ΔE total 246.8; preserves order: no
- Tritanopia: ΔE total 273.6; preserves order: no

## Related

- Family: https://colorcurio.us/colormaps/families/ncar
- All colormaps: https://colorcurio.us/colormaps