# How to read the semantic buffer?

**URL:** <https://community.nianticspatial.com/t/how-to-read-the-semantic-buffer/483>\
**Category:** I'm Stuck\
**Created:** [November 10, 2021, 8:39pm UTC](https://community.nianticspatial.com/t/how-to-read-the-semantic-buffer/483 "2021-11-10T20:39:32Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Jelmer\_Verhoog](https://avatars.discourse-cdn.com/v4/letter/j/b38774/32.png) [@Jelmer\_Verhoog](https://community.nianticspatial.com/u/Jelmer_Verhoog)\
**Post date:** [November 10, 2021, 8:39pm UTC](https://community.nianticspatial.com/t/how-to-read-the-semantic-buffer/483/1 "2021-11-10T20:39:32Z")

</div>

_Include the following details (edit as applicable):_

- **Issue category** : Semantic Segmentation
- **Device type & OS version** : iOS15.1 on iPhone 12 Pro
- **Host machine & OS version** : Mac
- **Issue Environment** : Native XCode build (=on device?)
- **Xcode version** : 13.0
- **ARDK version** : 0.9
- **Unity version** : 2019.4

Description of the issue:  
I’m unsure how to read the semantic buffer correctly.  
I have the RAW image in place to visualize the buffer and it looks correct.  
To debug the readout, I’m feeding a touch.position and checking the boolean. However it gives results that don’t correspond to what the RAW Image is showing on screen.  
What am I doing wrong?

```auto
using UnityEngine;
using UnityEngine.UI;
using Niantic.ARDK.Extensions;

public class SemanticDebug : MonoBehaviour
{
    [SerializeField]
    Text debugText;

    [SerializeField]
    ARSemanticSegmentationManager arSemanticSegmentationManager;

    bool result;

    void Update()
    {
        if (Input.touchCount > 0)
        {
            Touch touch = Input.GetTouch(0);

            if (touch.phase == TouchPhase.Moved)
            {
                result = arSemanticSegmentationManager.LatestSemanticBuffer.DoesChannelExistAt(touch.position, Screen.width, Screen.height, 1);
                debugText.text = $"result is: {result} for {touch.position}";
            }
        }
    }
}

```

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<div class="post-metadata">

**Author:** ![Michel\_Collina](https://avatars.discourse-cdn.com/v4/letter/m/7cd45c/32.png) [@Michel\_Collina](https://community.nianticspatial.com/u/Michel_Collina)\
**Post date:** [November 10, 2021, 11:49pm UTC](https://community.nianticspatial.com/t/how-to-read-the-semantic-buffer/483/2 "2021-11-10T23:49:01Z")

</div>

Hi!  
I’m a normal user, just like you, but i hope i could help.

I suggest you to look at the [‘Querying Semantic Tutorial’](https://lightship.dev/docs/basic_querying_semantics_tutorial.html) in the official documentation.  
Basically i suggest you to use the ‘PlatformAgnosticInput’ (instead of the Unity Input) and use the ‘arSemanticSegmentationManager.SemanticBufferProcessor.GetChannelNamesAt(x, y);’ function to get the channel’s name. I’ll leave below the official documentation’s code.

```auto
void Update()
    {
        if (PlatformAgnosticInput.touchCount <= 0) { return; }
 
        var touch = PlatformAgnosticInput.GetTouch(0);
        if (touch.phase == TouchPhase.Began)
        {
            //list the channels that are available
            Debug.Log("Number of Channels available " + _semanticManager.SemanticBufferProcessor.ChannelCount);
            foreach (var c in _semanticManager.SemanticBufferProcessor.Channels)
                Debug.Log(c);
 
 
            int x = (int)touch.position.x;
            int y = (int)touch.position.y;
 
            //return the indices
            int[] channelsInPixel = _semanticManager.SemanticBufferProcessor.GetChannelIndicesAt(x, y);
            
            //print them to console
            foreach (var i in channelsInPixel)
                Debug.Log(i);
 
            //return the names
            string[] channelsNamesInPixel = _semanticManager.SemanticBufferProcessor.GetChannelNamesAt(x, y);
 
            //print them to console
            foreach (var i in channelsNamesInPixel)
                Debug.Log(i);
 
        }
 
    }

```

Hope I was helpful,  
Cheers.

---

<div class="post-metadata">

**Author:** ![Jelmer\_Verhoog](https://avatars.discourse-cdn.com/v4/letter/j/b38774/32.png) [@Jelmer\_Verhoog](https://community.nianticspatial.com/u/Jelmer_Verhoog)\
**Post date:** [November 14, 2021, 8:23pm UTC](https://community.nianticspatial.com/t/how-to-read-the-semantic-buffer/483/3 "2021-11-14T20:23:46Z")

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Thanks, that was an excellent tip!  
That SemanticBufferProcessor did the trick.

Would you happen to know how to pause/temporarily switch off the semantic system? I’m not sure if disabling the ARSemanticSegmentationmanager stops the underlying processes…?

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<div class="post-metadata">

**Author:** ![system](https://sea2.discourse-cdn.com/niantic/user_avatar/community.nianticspatial.com/system/32/13_2.png) [@system](https://community.nianticspatial.com/u/system)\
**Post date:** [November 14, 2021, 10:23pm UTC](https://community.nianticspatial.com/t/how-to-read-the-semantic-buffer/483/4 "2021-11-14T22:23:51Z")

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