# contour3m

Project 3-D contour plot of map data

## Description

The `contour3m` function is the same as the `contourm` function except that the lines for each contour level are drawn in their own horizontal plane, at the z-coordinate equal to the value of that level.

## Examples

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Get geoid heights and a geographic postings reference object from the EGM96 geoid model. Then, create a 3-D contour plot with 40 contour levels using a Miller projection. Eliminate extra white space using `tightmap`.

```[N,R] = egm96geoid; axesm miller contour3m(N,R,40,'LineColor','k') tightmap```

Add the geoid as a surface, exaggerate the aspect ratio of the axes using `daspect`, and view the map in 3-D.

```hold on geoshow(N,R,'DisplayType','surface') daspect([1 1 50]) view(3)```

This example shows how to contour in a map axes the topography and bathymetry of South Asia and the northern Indian Ocean with a contour interval of 500 meters.

Load elevation raster data and a geographic cells reference object. Crop the data to an area around South Asia.

```load topo60c latlim = [0 50]; lonlim = [35 115]; [Z,R] = geocrop(topo60c,topo60cR,latlim,lonlim);```

Display the data as a contour plot using a standard Lambert conformal conic projection.

```figure axesm('lambertstd','MapLatLimit',latlim,'MapLonLimit',lonlim) tightmap axis off contour3m(Z,R,'k','LevelStep',500)```

Display the topography as a surface. Apply a colormap appropriate for elevation data using the `demcmap` function. Then, add a title.

```geoshow(Z,R,'DisplayType','surface') demcmap(Z) title({'South Asia Topography and Bathymetry', ... 'with 500 m Contours'});```

View the display in 3-D.

```set(gca,'DataAspectRatio',[1 1 40000]) view(3)```

## Tips

• If you use `contour3m` with the `globe` map display, the `contour3m` function warns. Be careful to scale the input data relative to the radius of your reference sphere.