Get the Image Data of an Imported PDF of Image in Revit using the ImageInstance and ImageType Classes

SEPTEMBER 5, 2019

Revit allows you to import PDF and image files from its Ribbon menu. After clicking either button (Import PDF or Import Image) you get the same window, really, just with a different extension pre-selected.

You import a file and place it into a view, and if the file happens to be a PDF file you select a page and a rasterization resolution (in DPI).

Internally, Revit uses the PDFNet library made by PDFTron to manipulate PDF files. One of the operations it seems to use it for is to rasterize the contents of a PDF to be able to display it on a view. This process makes the image data (of the image itself or a rasterized PDF) available inside of Revit. By using the Revit Lookup add-in, I found that the ImageType class offers a GetImage() method which returns a Bitmap object containing that image data.


Remember that, when you pick an existing imported image or PDF, you are selecting what's called an object of the ImageInstance class, which wraps an ImageType object. So we need to get the ImageInstance element, access its ImageType, then get its image data.


Let's see the code.

// This code goes somewhere in your Revit add-in
// Prompt user to pick a Revit Element
Reference pickedObject = UIDoc.Selection.PickObject(Autodesk.Revit.UI.Selection.ObjectType.Element);

// Get Element
Element element = Doc.GetElement(pickedObject.ElementId);

// Get Element Type
ElementId elementTypeId = element.GetTypeId();
ElementType elementType = Doc.GetElement(elementTypeId) as ElementType;

// Do something if object selection exists
if (pickedObject != null)
{
    // Check if picked element is an ImageInstance
    if (element is ImageInstance)
    {
        // Cast types for ImageInstance and ImageType
        // ImageType Id = ImageInstance Id - 1
        ImageInstance image = element as ImageInstance;
        ImageType imageType = elementType as ImageType;

        // Get image properties
        var filename = image.Name; // eg. FloorPlan.pdf

        // Get imported file path from ImageType
        var filepath = imageType.get_Parameter(BuiltInParameter.RASTER_SYMBOL_FILENAME).AsString();
        var pixelWidth = imageType.get_Parameter(BuiltInParameter.RASTER_SYMBOL_PIXELWIDTH).AsInteger();
        var pixelHeight = imageType.get_Parameter(BuiltInParameter.RASTER_SYMBOL_PIXELHEIGHT).AsInteger();

        // Get image data
        Bitmap bitmap = imageType.GetImage();

        // Save image to disk
        bitmap.Save(@"C:\users\username\Desktop\image.bmp");
    }
}

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