Using Autotags in PIX4Dcatch

 

What are Autotags?

Autotags are coded visual markers that the PIX4Dcatch app can detect and mark automatically. When used in the field, they provide a reliable way to mark known reference points, reducing the need for manual tagging and ensuring consistent detection across multiple images.

                               

We recommend printing on A4-size or US Letter-sized paper for optimal compatibility.

Printable Autotags are available for download:

• A4 size PDF
  
  
• US Letter size PDF

Best Practices for Using Autotags in PIX4Dcatch

Placement Guidelines

Proper Autotag placement is critical for accurate detection and reliable results:

• Distribute Autotags evenly across the project area.
  
  
• Ensure Autotags are clean, flat, and not obstructed by shadows or objects.
  
  
• Avoid blurry images. Ensure each tag is clearly visible and sharp.
  
  
• Make sure tags are large enough to appear clearly in the captured images.
  
  
• Maintain a good image overlap so each tag appears in multiple images.
  
  
• Avoid placing unused Autotags within view, as they may interfere with detection.
  
  
• Do not place Autotags at the very edges of the project area. They may not appear in a sufficient number of images.

Tag Distribution Example

Think of your project area as a table, with Autotags as its legs. Clustered legs make it unstable, while evenly spaced ones keep it balanced. For best results, distribute Autotags evenly across the area and, if possible, place one near the center to enhance model stability.

Recommended setup:

• Minimum: 3 Autotags (required for processing).
  
  
• Recommended: 5–10 Autotags for improved accuracy.
  
  

Corridors: Offset the tags along the length and place a pair at each end.

How to enable the Tag Detection feature

PIX4Dcatch can automatically detect Autotags during image capture if the Tag Detection feature is enabled. Enabling this feature without importing a Point Collection for GCPs will create MTPs.

1. Go to Capture Mode.
2. Tap the Tools menu.
3. Select Tag Detection.
   
   
4. Enable Detect Autotags.
   
   
   

A confirmation will appear showing that Autotag detection is active.

   

How to enable GCPs with Tag Detection feature

In PIX4Dcatch, a list of GCPs is known as a Point Collection. For the automatic detection of GCPs to work, the Point Collection must be imported and linked to the Autotags.

1.  After the Tag Detection feature is enabled, tap Import Point Collection.
   
2. Select point Collection from the list
   
   
3. Once imported, tap Done.
   

Example:

• PointName_1 corresponds to Autotag 01
• PointName_2 corresponds to Autotag 02
• PointName_3 corresponds to Autotag 03

During Capture

While moving around the site:

• PIX4Dcatch will mark detected Autotags in real-time.
  
  
• Tags with green labels indicate valid detections.
  
  
• Below the Signal Indicator dialog, the total number of successfully marked Autotags and the number of point entries in the Point Collection are displayed.
  
  

Optimizing Autotag Detection

After capture, PIX4Dcatch gives the option to optimize Autotag detection. This step improves marker precision and strengthens the 3D model reconstruction. This step can be performed immediately or at a later time.

How to Optimize Autotag Detection

1. Tap the more options icon in the upper-right corner of the project. 
2. Select Optimize Autotags detection.
   
   
3. A progress bar will be shown.
   
   

 Optimize Autotags When Saving

PIX4Dcatch allows automatic optimization of Autotag detection when saving a project. Enabling this option ensures improved accuracy without requiring manual intervention. 

To configure automatic optimization when saving:

1. Go to Main Menu > Project Settings.
   
   
2. Tap Optimize Autotags When Saving.
   
   
3. Choose one of the following:
   
   
         

Ask each time – Display a prompt before optimizing.
Skip – Do not optimize when saving.

Always – Automatically optimize upon saving.