Hello, World!

In this article, you will learn how to build 2 simple C++ applications for creating and recognizing a simple questionnaire with Aspose.OMR for C++.

You will need

  • A compatible OS with Microsoft Visual Studio installed. As an individual developer, you can use a free Visual Studio Community Edition.
  • A printer for producing printed forms.
  • A pen, a pencil, or a marker for filling answer bubbles.
  • A smartphone with a high-resolution camera.
  • 15 minutes of spare time.

Steps to be taken

While our OMR application requires minimal coding, the underlying process is a bit more complex than the typical Hello World. Let’s look at the necessary steps to be taken.

Necessary steps to be taken

  1. Design the questionnaire.
  2. Generate a printable form and recognition pattern files.
  3. Print the form.
  4. Fill the form.
  5. Scan or take a photo of the form.
  6. Recognize the form.

Designing the questionnaire

Aspose.OMR for C++ not only performs recognition, but also allows you to design OMR forms of any layout and complexity.

The structure and layout of the questionnaire (template source) is defined in a plain-text file that uses a special notation. You can create it with any text editor, including Notepad or Visual Studio.

?text=Hello, World!
	font_style=bold
	font_size=24
	align=center

#How are you doing today?
	() Pretty good, thanks! () I won't respond until I see my lawyer.

In this article, we won’t delve into the full syntax of the template. Let’s just take a look at its key building blocks:

  • The text after ?text= keyword is rendered as a simple paragraph. You can optionally format it by adding layout attributes (font, style, and the like) on the lines immediately following the text. Each attribute definition must be preceded by a tab character.
  • The question text is provided on a new line starting with a hash (#). The hash itself is not rendered.
  • The answers are provided on new lines immediately following the question. You can either place all answers on a single line or on several lines by adding line breaks. Each line must begin with a tab character.

Save the template source somewhere on you disk under the name template.txt. You will need it on the next step.

Generating a form

Once you have finished with the questionnaire structure and layout, let’s build a simple utility that generates a printable form from it.

  1. Create a console C++ project in Visual Studio.
  2. Install Aspose.OMR.Cpp NuGet package to the project.
  3. Copy a form template file (template.txt) created on the previous step into the build directory of the project.
  4. Initialize Aspose.OMR for C++ engine: 
    System::SharedPtr<Api::OmrEngine> engine = System::MakeObject<Api::OmrEngine>();
  5. Generate a form from the template source file: 
    System::SharedPtr<Generation::GenerationResult> result = engine->GenerateTemplate(u"template.txt");
  6. Save the result: 
    result.Save("target", "omr-form");

Full listing:

// Initialize OMR engine
System::SharedPtr<Api::OmrEngine> engine = System::MakeObject<Api::OmrEngine>();
// Generate and save printable form and recognition pattern file
System::SharedPtr<Generation::GenerationResult> result = engine->GenerateTemplate(u"template.txt");
result.Save("target", "omr-form");

Now run the program. If the template is correct, you should get 2 files in bin\Debug directory of the project:

  • omr-form.png
    A printable form in PNG format. Since we have not provided a license, there will be a watermark on the page.
    Printable form
  • omr-form.omr
    A recognition pattern used by Aspose.OMR recognition engine. This file is required for recognizing filled forms, make sure you do not accidentally delete it!

Answering the questionnaire

Let’s take a break from the computer and get back to the good old pen and paper.

  1. Print the form (Hello.OMR.png) generated on the previous step.
  2. Mark an answer bubble.
  3. Take a photo of the filled form (the entire sheet with all 4 crop marks) with your smartphone.
    Filled form - photo

Recognizing the questionnaire

Now we are ready for what OMR stands for – optical mark recognition.

  1. Create a console C++ project in Visual Studio.
  2. Install Aspose.OMR.Cpp NuGet package to the project.
  3. Copy the photo of the filled form (for example, IMG_20220401.jpg) into the build directory of the project.
  4. Copy the previously generated recognition pattern (omr-form.omr) into the build directory of the project.
  5. Initialize Aspose.OMR for C++ engine: 
    System::SharedPtr<Api::OmrEngine> engine = System::MakeObject<Api::OmrEngine>();
  6. Load the recognition pattern from omr-form.omr file: 
    System::SharedPtr<Api::TemplateProcessor> processor = engine->GetTemplateProcessor(u"omr-form.omr");
  7. Recognize the photo of the filled form: 
    System::SharedPtr<Model::RecognitionResult> result = processor->RecognizeImage(u"IMG_20220401.jpg");
  8. Convert the recognition result to comma-separated values (CSV) format: 
    System::String resultCsv = result->GetCsv();

Full listing:

// Initialize OMR engine
System::SharedPtr<Api::OmrEngine> engine = System::MakeObject<Api::OmrEngine>();
// Load recognition pattern file
System::SharedPtr<Api::TemplateProcessor> processor = engine->GetTemplateProcessor(u"omr-form.omr");
// Recognized completed survey
System::SharedPtr<Model::RecognitionResult> result = processor->RecognizeImage(u"IMG_20220401.jpg");
// Get results in CSV format
System::String resultCsv = result->GetCsv();

Recognition result

Now run the program. You should get the following recognition results:

Element Name,Value,
Question1,"A"

What’s next?

Congratulations! You have taken the first steps in optical mark recognition technology. Read the Developer reference and API reference for details on developing advanced OMR forms and applications with Aspose.OMR for C++.

Licensing