# Plotting a 3D surface in Cartesian coordinates from a polar-grid data

**URL:** <https://discourse.julialang.org/t/plotting-a-3d-surface-in-cartesian-coordinates-from-a-polar-grid-data/22184>\
**Category:** New to Julia\
**Tags:** visualization\
**Created:** [March 22, 2019, 7:57am UTC](https://discourse.julialang.org/t/plotting-a-3d-surface-in-cartesian-coordinates-from-a-polar-grid-data/22184 "2019-03-22T07:57:10Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Aleksandr\_Mikheev](https://avatars.discourse-cdn.com/v4/letter/a/b4bc9f/32.png) [@Aleksandr\_Mikheev](https://discourse.julialang.org/u/Aleksandr_Mikheev)\
**Post date:** [March 22, 2019, 7:57am UTC](https://discourse.julialang.org/t/plotting-a-3d-surface-in-cartesian-coordinates-from-a-polar-grid-data/22184/1 "2019-03-22T07:57:10Z")

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I have an irregular grid in polar coordinates, i.e. I have two arrays `r[100]` and `theta[200]` that define the grid and an array containing the data that I want to polt, `data[200,100]`. Is there any simple way to make a surface plot in Cartesian coordinates? Or at least in polar?

So, mathematically speaking, I have a function f(\theta,r) defined on the irregular grid (\theta\_i,r\_j), i = 1,\ldots,200, j = 1,\ldots,100 (actually, the (\cos \theta\_i, \log r\_j) grid is regular). And I would like to plot this function in, ideally, Cartesian coordinates. What would be the easiest way to do so? Thanks in advance for any help!