# Using Surface LIC: Attempt to get an input array for an index that has not been specified
**URL:** https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032
**Category:** ParaView Support
**Created:** [September 20, 2021, 12:08pm UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032 "2021-09-20T12:08:48Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@JulianSchl](https://discourse.paraview.org/u/JulianSchl)
#### Post date: [September 20, 2021, 12:08pm UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032/1 "2021-09-20T12:08:48Z")
Hi,
I’m trying to vizualize the velocity field of my CFD OpenFOAM results with the [LIC](https://www.paraview.org/Wiki/ParaView/Line_Integral_Convolution) addon.
In previous cases the visualization with LIC worked as expected.
I my current case, selecting “surface LIC” in Paraview, I’m getting the error:
```auto
Attempt to get an input array for an index that has not been specified
```
In the render window I’m getting weird grey blocks.
This issue was already mentioned [here](https://discourse.paraview.org/t/surface-lic-doesnt-work/3296) and [here](https://discourse.paraview.org/t/surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/6180).
As mentioned in previous discussions, LIC expects the scalars\_ field to be of dimension 3.
However in my case the scalars\_ fields is of dimension 4.
My questions are:
How could the scalars\_ fields differ in its dimensions using OpenFOAM?
And how can a Paraview user can solve this issue, e.g. change the scalars\_ dimension?
I’ve also added a vtp file to better coprehend the case: [moment.zip](https://discourse.paraview.org/uploads/short-url/rPSwRmC2Twzktg6BVlSKg4FAxgo.zip) (3.6 MB)
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 20, 2021, 12:17pm UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032/2 "2021-09-20T12:17:57Z")
Use the calculator filter to create a 3 component vector using your 4 component field.
---
### Author:  [@JulianSchl](https://discourse.paraview.org/u/JulianSchl)
#### Post date: [September 20, 2021, 12:37pm UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032/3 "2021-09-20T12:37:19Z")
Hi,
thank you for your reply!
When executing `U[:,:3]` in the Python calculator, I don’t get the error message, but the rendering window still shows weird blocks:
> **view screenshot**
>
> 
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 20, 2021, 1:04pm UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032/4 "2021-09-20T13:04:39Z")
Here is how it looks here, I do not see the blocks:
---
### Author:  [@JulianSchl](https://discourse.paraview.org/u/JulianSchl)
#### Post date: [September 21, 2021, 7:46am UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032/5 "2021-09-21T07:46:40Z")
Having tried it on another machine where it worked too,
I now think it is a problem on my machine.
When I save the state on the working machine and open it on the failing system, I can view the LIC.
But when I normally open the case.foam on that machine, I’m getting those weird blocks.
Still I do not understand, why I could use LIC without problems in the previous time.
Unloading and loading the plugin doesn’t help either ☹
I’m using Paraview 5.9.1 on Ubuntu 20.04.2 LTS.
---
### Author:  [@JulianSchl](https://discourse.paraview.org/u/JulianSchl)
#### Post date: [October 7, 2021, 11:57am UTC](https://discourse.paraview.org/t/using-surface-lic-attempt-to-get-an-input-array-for-an-index-that-has-not-been-specified/8032/6 "2021-10-07T11:57:34Z")
Hi,
solved it by resetting paraview, must’ve been a weird setting constellation.