Build Your First Flow

After learning the basics of using Nara and understanding the different parts of the Flow Page, the next step is to create a Flow from scratch by yourself. In this section, you will recreate the same Flow from the Deploy your First Flow (Quick Start) tutorial, but this time without using any templates.

In this Flow, you will build an Quick Start: General Object Detection by displaying both the processed image and the detected object count on the Dashboard through Variable Nodes.

Flow Overview

Steps to Build the Flow Manually

1. Create the Variable Image Node:
   Before creating the Flow Path, first create a Variable: Create Node since these Nodes act as intermediaries for transferring data between the Flow and the Dashboard. Configure the Node as shown below and rename it to Variable Image.

2. Create the Variable Count Node:
   This Node is used to store the number of detected objects in the image.

3. Add a Time Interval Trigger:
   Configure the Interval Value and Interval Unit based on how often you want the system to run. You can customize the settings as needed or follow the example below.

4. Add a Webcam Node:
   Configure the Node as shown below.

• By default, the Webcam Index is usually set to 0.
• After configuration, connect the Input of this Node to the Output of the Time Interval Trigger Node.
• This Node captures frames from the webcam and sends them to the next Node for processing.

5. Add a Stop Node:
   Connect the Error Output of the Webcam Node to the Stop Node to stop the Flow whenever an error occurs.

6. Add a General Object Detection Node:
   Configure the Input Image by referencing the Frame output from the Webcam Node. Then select the desired Model Size and choose the objects you want to detect.

This Node analyzes the image and outputs:

• The processed image with detection results
• The number of detected objects

7. Add a Variable Modify Image Node:
   Rename it to Variable Image: Modify and connect it to the Output of the General Object Detection Node.

• Configure this Node to update the value of Variable Image using the Output Frame from the General Object Detection Node.
• The updated value will be displayed on the Dashboard through the Variable Image Node created in Step 1.

8. Add a Variable Modify Count Node:
   Rename it to Variable Count: Modify and connect it to the Output of the General Object Detection Node.

• Configure this Node to update the value of Variable Count using the detectCount Output from the General Object Detection Node.
• The updated value will display the number of detected objects on the Dashboard.

9. Make sure all nodes are connected correctly as shown in the image below
   

10. Deploy the Flow

Steps to Build the Dashboard Manually

1. Go to the Dashboard page and click Edit at the top-right corner. Then select the Image Frame Widget, drag and drop it onto the Dashboard, and resize it as needed.

2. Configure the Image Frame Widget by setting the Data Source to Variable Image so it displays the processed webcam image with object detection results.

3. Add a Basic Widget to display the detected object count.

4. Configure the Basic Widget and set the Data Source > Variable Count.

Set up Value Conditional Formatting with the following conditions:

• > 0 → Display the count in green, indicating that a person has been detected
• = 0 → Display the count in red, indicating that no person has been detected

Congratulations! Your first Flow is complete