# vtkProjectedTerrainPath usage

**URL:** https://discourse.vtk.org/t/vtkprojectedterrainpath-usage/7144
**Category:** Support
**Created:** [November 10, 2021, 10:37pm UTC](https://discourse.vtk.org/t/vtkprojectedterrainpath-usage/7144 "2021-11-10T22:37:34Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![bistek](https://discourse.vtk.org/user_avatar/discourse.vtk.org/bistek/32/2344_2.png) [@bistek](https://discourse.vtk.org/u/bistek)
#### Post date: [November 10, 2021, 10:37pm UTC](https://discourse.vtk.org/t/vtkprojectedterrainpath-usage/7144/1 "2021-11-10T22:37:34Z")

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Hello, we are trying to use vtkProjectedTerrainPath to vertically project a polyline onto a digital elevation model, but our input terrain data is a vtkStructuredGrid and a 2D height image is required instead ([see documentation here](https://vtk.org/doc/nightly/html/classvtkProjectedTerrainPath.html#details)).

We can imagine two options:

1. Converting the structured grid to a suitable 2D image (not clear how to do this and in any case the image will be heavy).

2. Using a different interpolation algorithm (which one?).

Suggestions and examples are welcome, thanks!