[v1] About Templates - Udayraj123/OMRChecker GitHub Wiki

Meaning of parameters used in the template.json file

Let's take an example of sample1 from the samples.

You may use below commands from project root to load the sample template.

python3 main.py -i samples/sample1 --setLayout

Which shows the template overlay like below -

Let's examine the template.json used in this sample.

{
  // The dimensions(width, height) to which the page will be resized to before applying template
  "pageDimensions": [
    1846,
    1500
  ],
  // The dimensions of the overlay bubble area
  "bubbleDimensions": [
    40,
    40
  ],
  // Custom configuration values to use in the template's directory
  "preProcessors": [
    {
      // Page boundary based cropping plugin
      "name": "CropPage",
      "options": {
        // size of the kernel to use for cropping (default for most cases)
        "morphKernel": [
          10,
          10
        ]
      }
    },
    {
      // Marker based cropping plugin
      "name": "CropOnMarkers",
      "options": {
        // path to marker file
        "relativePath": "omr_marker.jpg",
        // a factor by which marker shall be resized relative to input image 
        "sheetToMarkerWidthRatio": 17
      }
    }
  ],
  
// The customLabels contain fields that need to be joined together before generating the results sheet
  "customLabels": {
    // Here the "Roll" key corresponds to a single column in the results
    "Roll": [
      "Medium",
      "roll1",
      "roll2",
      "roll3",
      "roll4",
      "roll5",
      "roll6",
      "roll7",
      "roll8",
      "roll9"
    ],
    // customLabels can also be used for two-digit integer type questions.
    "q5": [
      "q5_1",
      "q5_2"
    ],
    // ...
  },
  // Each rectangular box you see in the template overlay image is an item in fieldBlocks 
  "fieldBlocks": {
    // ...

    // Create a block of MCQ type questions

    "MCQ_Block_Q1": {
      // Here, QTYPE_MCQ4 is a built-in field type with four values ["A", "B", "C", "D"]
      "fieldType": "QTYPE_MCQ4",
      // The ordered questions in this block (length of this array is the number of questions in this block)
      "fieldLabels": ["q1", "q2", "q3", "q4"],
      // The gaps between the bubbles
      "bubblesGap": 59,
      // The gaps between the labels i.e. the mcq questions
      "labelsGap": 50,
      // The starting point of the block (top left)
      "origin": [121, 860]
    },
    
    // This shows how integer type questions are created.
    "Int_Block_Q5": {
      // Here, QTYPE_INT is a built-in field type with vertical arrangement of 0-9 integers
      "fieldType": "QTYPE_INT",
      // These field labels will concatenated together as declared in customLabels earlier.
      "fieldLabels": ["q5_1", "q5_2"],
      // The gaps between the bubbles
      "bubblesGap": 46,
      // The gaps between the labels i.e. the two integer columns
      "labelsGap": 60,
      // The starting point of the block (top left)
      "origin": [903, 282]
    },

    // A custom field
    "Medium": {
      // The starting point of the block (top left)
      "origin": [
        170,
        282
      ],
      // The direction of the bubbles
      "direction": "vertical",
      // The gaps between the bubbles
      "bubblesGap": 41,
      // Custom values for the bubbles (length of this array is the number of bubbles per field)
      "bubbleValues": ["E", "H"],
      // The labels for fields in the block 
      "fieldLabels": ["Medium"],
      // Since we have only one label in this block, we set labelsGap as 0
      "labelsGap": 0,
    },

    // ... rest of the fieldBlocks
  },
  // All the columns in order(custom and non-custom) to be outputted in the results sheet
  "outputColumns": [
    "Roll",
    "q1",
    "q2",
    // ...
  ],
  // The value to be used in case of empty bubble detected
  "emptyValue": ""
}

More details

You can find the full template schema in the source code.