# BitArray{3} mesh
**URL:** https://discourse.julialang.org/t/bitarray-3-mesh/49697
**Category:** New to Julia
**Tags:** package, mesh
**Created:** [November 6, 2020, 6:30pm UTC](https://discourse.julialang.org/t/bitarray-3-mesh/49697 "2020-11-06T18:30:11Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@dalarev](https://discourse.julialang.org/u/dalarev)
#### Post date: [November 6, 2020, 6:30pm UTC](https://discourse.julialang.org/t/bitarray-3-mesh/49697/1 "2020-11-06T18:30:11Z")
What is the recommended process to mesh a BitArray?
The meshing method requires an `isovalue`. For a BitArray, an `isovalue` of `1`, `true` or `:true` don’t seem to work: 0 faces are returned.
Another method is to convert from BitArray to an Array: `MyData = 1MyData`. Then `isovalue=0.5` could work.
In general, is `isovalue` to be interpreted as “everything in `MyArray .>= isovalue`”?
Thanks!
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### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [November 8, 2020, 12:55pm UTC](https://discourse.julialang.org/t/bitarray-3-mesh/49697/2 "2020-11-08T12:55:33Z")
> [@dalarev](#):
>
> mesh a BitArray
I don’t know what this means. Lack of context may be the reason why you are not getting answers to this.
> [@Please read: make it easier to help you](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757/):
>
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### Author:  [@dalarev](https://discourse.julialang.org/u/dalarev)
#### Post date: [November 9, 2020, 3:00pm UTC](https://discourse.julialang.org/t/bitarray-3-mesh/49697/3 "2020-11-09T15:00:19Z")
You’re right, thanks for the reminder, Tamas. Couldn’t edit my post, so here’s a MWE:
```julia
# Packages
using Random
using Meshing
using GeometryBasics
using Makie#master
# Generate Mesh
A = bitrand(5,5,5)
algo = MarchingCubes(iso=1, insidepositive=true)
vertices, faces = isosurface(A, algo, Point{3,Float32}, TriangleFace{Int})
m = GeometryBasics.Mesh(vertices,faces)
# Visualize Mesh
Makie.mesh(m, color=:blue, shading=false)
Makie.wireframe!(m)
```
Question is: why doesn’t `iso=1` work given that this is a BitArray? It returns 0 faces.
After playing with the isovalue, I see that any value `0 <= iso < 1` will return a consistent number of faces. I am a bit puzzled as to why `iso=1` does not work.
I guess I’m looking to answer the general question of how the isovalue is interpreted. Is it `A .>= iso`?
Much appreciated!
edit: I wonder if it has to do with the [default tolerance](https://juliageometry.github.io/Meshing.jl/stable/api/#Meshing.MarchingCubes) `eps = 1e-3`. It breaks down when it can’t find a value greater than 1 in a boolean array. If I set `eps=0`, `iso=1` still does not work.
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### Author:  [@Jeff\_Emanuel](https://discourse.julialang.org/u/Jeff_Emanuel)
#### Post date: [November 9, 2020, 5:44pm UTC](https://discourse.julialang.org/t/bitarray-3-mesh/49697/4 "2020-11-09T17:44:45Z")
Your isosurface should follow grid edges between nodes with value 1 which are connected nodes with value 0. Since marching cubes doesn’t seem to like this situation where there is no value greater than 1, I would just set iso to some value close to but less than 1, say 0.999 and then round-up all the resulting isosurface coordinates to the nearest grid node.
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### Author:  [@dalarev](https://discourse.julialang.org/u/dalarev)
#### Post date: [November 9, 2020, 8:22pm UTC](https://discourse.julialang.org/t/bitarray-3-mesh/49697/5 "2020-11-09T20:22:06Z")
Yes, that seems to work. As I mention in my previous post, any value `0 <= iso < 1` will work (and produce the same results), so I suppose this is the solution in this case.
Just as an additional data point, when visualizing with `Makie.volume`, `isovalue=1` _will_ work.