VtkRaster Class Reference

Detailed Description

Loading raster data such as images or ArcGIS-data into VTK image data structures.

The VtkRaster class enables loading of raster data such as images or ArcGIS-data. Supported image formats are ..... Georeferenced data can be imported via the GeoTIFF- or asc-format.

Definition at line 29 of file VtkRaster.h.

#include <VtkRaster.h>

Static Public Member Functions
static vtkImageImport *	loadImageFromArray (double const *const data_array, GeoLib::RasterHeader header)
	Returns a VtkImageAlgorithm from an array of pixel values and some image meta data.
static vtkImageAlgorithm *	loadImage (const std::string &fileName)
	Loads an image- or raster-file into an vtkImageAlgorithm-Object.

Static Private Member Functions
static vtkImageAlgorithm *	loadImageFromTIFF (const std::string &fileName)
static vtkImageReader2 *	loadImageFromFile (const std::string &fileName)
static std::string	findWorldFile (const std::string &filename)
static bool	readWorldFile (std::string const &filename, vtkImageReader2 *image)

Member Function Documentation

findWorldFile()

std::string VtkRaster::findWorldFile ( const std::string & filename )

staticprivate

Tries to find a world file for the image given by the filename. World files can have a number of extensions depending on the programme used to write the image and this method just cycles through the possibilities, returning the first match it finds.

Definition at line 329 of file VtkRaster.cpp.

{
    std::string const no_ext = BaseLib::dropFileExtension(filename);
 
    constexpr std::array supported_extensions = {
        ".pgw",  ".pngw", ".pgwx", ".jgw",  ".jpgw", ".jgwx", ".tfw",
        ".tifw", ".tfwx", ".bpw",  ".bmpw", ".bpwx", ".wld"};
 
    auto const res =
        std::find_if(supported_extensions.begin(), supported_extensions.end(),
                     [&no_ext](auto const& ext) -> bool
                     { return BaseLib::IsFileExisting(no_ext + ext); });
    if (res != supported_extensions.end())
    {
        return no_ext + *res;
    }
 
    // no world file found
    return {};
}

References BaseLib::dropFileExtension().

Referenced by readWorldFile().

loadImage()

vtkImageAlgorithm * VtkRaster::loadImage ( const std::string & fileName )

static

Loads an image- or raster-file into an vtkImageAlgorithm-Object.

Public method for loading all data formats. Internally the method automatically differentiates between images and georeferenced files and then calls the appropriate method for reading the file.

Parameters

fileName

Filename of the file that should be loaded.

Returns

The ImageAlgorithm-object.

Definition at line 43 of file VtkRaster.cpp.

{
    QFileInfo fileInfo(QString::fromStdString(fileName));
 
    std::unique_ptr<GeoLib::Raster> raster(nullptr);
    if (fileInfo.suffix().toLower() == "asc")
    {
        raster.reset(
            FileIO::AsciiRasterInterface::getRasterFromASCFile(fileName));
    }
    else if (fileInfo.suffix().toLower() == "grd")
    {
        raster.reset(
            FileIO::AsciiRasterInterface::getRasterFromSurferFile(fileName));
    }
    else if (fileInfo.suffix().toLower() == "xyz")
    {
        raster.reset(
            FileIO::AsciiRasterInterface::getRasterFromXyzFile(fileName));
    }
    if (raster)
    {
        return VtkRaster::loadImageFromArray(raster->data(),
                                             raster->getHeader());
    }
    if ((fileInfo.suffix().toLower() == "tif") ||
        (fileInfo.suffix().toLower() == "tiff"))
    {
#ifdef GEOTIFF_FOUND
        return loadImageFromTIFF(fileName);
#else
        ERR("VtkRaster::loadImage(): GeoTiff file format not supported in this "
            "version! Trying to parse as Tiff-file.");
        return loadImageFromFile(fileName);
#endif
    }
 
    return loadImageFromFile(fileName);
}

References ERR(), FileIO::AsciiRasterInterface::getRasterFromASCFile(), FileIO::AsciiRasterInterface::getRasterFromSurferFile(), FileIO::AsciiRasterInterface::getRasterFromXyzFile(), loadImageFromArray(), loadImageFromFile(), and loadImageFromTIFF().

Referenced by VtkCompositeTextureOnSurfaceFilter::init(), MainWindow::loadFile(), and VtkGeoImageSource::readImage().

loadImageFromArray()

vtkImageImport * VtkRaster::loadImageFromArray ( double const *const data_array, GeoLib::RasterHeader header )

static

Returns a VtkImageAlgorithm from an array of pixel values and some image meta data.

Definition at line 82 of file VtkRaster.cpp.

{
    const unsigned length = header.n_rows * header.n_cols * header.n_depth;
    auto* data = new float[length * 2];
    float max_val =
        static_cast<float>(*std::max_element(data_array, data_array + length));
    for (unsigned j = 0; j < length; ++j)
    {
        data[j * 2] = static_cast<float>(data_array[j]);
        if (fabs(data[j * 2] - header.no_data) <
            std::numeric_limits<double>::epsilon())
        {
            data[j * 2] = max_val;
            data[j * 2 + 1] = 0;
        }
        else
        {
            data[j * 2 + 1] = max_val;
        }
    }
 
    vtkImageImport* image = vtkImageImport::New();
    image->SetDataSpacing(header.cell_size, header.cell_size, header.cell_size);
    image->SetDataOrigin(header.origin[0] + (header.cell_size / 2.0),
                         header.origin[1] + (header.cell_size / 2.0),
                         0);  // translate whole mesh by half a pixel in x and y
    image->SetWholeExtent(0, header.n_cols - 1, 0, header.n_rows - 1, 0,
                          header.n_depth - 1);
    image->SetDataExtent(0, header.n_cols - 1, 0, header.n_rows - 1, 0,
                         header.n_depth - 1);
    image->SetDataExtentToWholeExtent();
    image->SetDataScalarTypeToFloat();
    image->SetNumberOfScalarComponents(2);
    image->SetImportVoidPointer(data, 0);
    image->Update();
 
    return image;
}

References GeoLib::RasterHeader::cell_size, GeoLib::RasterHeader::n_cols, GeoLib::RasterHeader::n_depth, GeoLib::RasterHeader::n_rows, GeoLib::RasterHeader::no_data, and GeoLib::RasterHeader::origin.

Referenced by NetCdfConfigureDialog::createDataObject(), and loadImage().

loadImageFromFile()

vtkImageReader2 * VtkRaster::loadImageFromFile ( const std::string & fileName )

staticprivate

Loads image files into a QPixmap object. Since images are not geo-referenced no origin point will be returned.

Parameters

fileName

Filename of the file that should be loaded.

Returns

vtkImageReader2-object containing the image data.

Definition at line 291 of file VtkRaster.cpp.

{
    QString file_name(QString::fromStdString(fileName));
    QFileInfo fi(file_name);
    vtkImageReader2* image(nullptr);
 
    if (fi.suffix().toLower() == "png")
    {
        image = vtkPNGReader::New();
    }
    else if ((fi.suffix().toLower() == "tif") ||
             (fi.suffix().toLower() == "tiff"))
    {
        image = vtkTIFFReader::New();
    }
    else if ((fi.suffix().toLower() == "jpg") ||
             (fi.suffix().toLower() == "jpeg"))
    {
        image = vtkJPEGReader::New();
    }
    else if (fi.suffix().toLower() == "bmp")
    {
        image = vtkBMPReader::New();
    }
    else
    {
        ERR("VtkRaster::readImageFromFile(): File format not supported, please "
            "convert to BMP, JPG, PNG or TIFF.");
        return nullptr;
    }
 
    image->SetFileName(fileName.c_str());
    image->GetOutput()->AllocateScalars(VTK_FLOAT, 1);
    image->Update();
    readWorldFile(fileName, image);
    return image;
}

References ERR(), and readWorldFile().

Referenced by loadImage().

loadImageFromTIFF()

vtkImageAlgorithm * VtkRaster::loadImageFromTIFF ( const std::string & fileName )

staticprivate

Loads ArcGIS asc-files to a QPixmap object and automatically does a contrast stretching to adjust values to 8 bit greyscale images.

Parameters

fileName

Filename of the file that should be loaded.

Returns

A vtkImageImport-object (derived from vtkImageAlgorithm).

Definition at line 123 of file VtkRaster.cpp.

{
    TIFF* tiff = XTIFFOpen(fileName.c_str(), "r");
 
    if (tiff)
    {
        GTIF* geoTiff = GTIFNew(tiff);
 
        int version[3];
        int count(0);
        GTIFDirectoryInfo(geoTiff, version, &count);
 
        if (count == 0)
            WARN("VtkRaster::loadImageFromTIFF - file is not georeferenced.");
 
        if (geoTiff)
        {
            double x0 = 0.0;
            double y0 = 0.0;
            double cellsize = 1.0;
            int imgWidth = 0;
            int imgHeight = 0;
            int nImages = 0;
            int pntCount = 0;
            double* pnts = nullptr;
 
            // get actual number of images in the tiff file
            do
            {
                ++nImages;
            } while (TIFFReadDirectory(tiff));
            if (nImages > 1)
                INFO(
                    "VtkRaster::loadImageFromTIFF() - File contains {:d} "
                    "images. This method is not tested for this case.",
                    nImages);
 
            // get image size
            TIFFGetField(tiff, TIFFTAG_IMAGEWIDTH, &imgWidth);
            TIFFGetField(tiff, TIFFTAG_IMAGELENGTH, &imgHeight);
 
            // get cellsize
            // Note: GeoTiff allows anisotropic pixels. This is not supported
            // here and equilateral pixels are assumed.
            if (TIFFGetField(tiff, GTIFF_PIXELSCALE, &pntCount, &pnts))
            {
                if (pnts[0] != pnts[1])
                    WARN(
                        "VtkRaster::loadImageFromTIFF(): Original raster data "
                        "has anisotrop pixel size!");
                cellsize = pnts[0];
            }
 
            // get upper left point / origin
            if (TIFFGetField(tiff, GTIFF_TIEPOINTS, &pntCount, &pnts))
            {
                x0 = pnts[3];
                y0 = pnts[4] -
                     (imgHeight * cellsize);  // the origin should be the lower
                                              // left corner of the img
            }
 
            // read pixel values
            auto* pixVal = static_cast<uint32*>(
                _TIFFmalloc(imgWidth * imgHeight * sizeof(uint32)));
            if ((imgWidth > 0) && (imgHeight > 0))
            {
                if (!TIFFReadRGBAImage(tiff, imgWidth, imgHeight, pixVal, 0))
                {
                    ERR("VtkRaster::loadImageFromTIFF(): reading GeoTIFF "
                        "file.");
                    _TIFFfree(pixVal);
                    GTIFFree(geoTiff);
                    XTIFFClose(tiff);
                    return nullptr;
                }
            }
 
            // check for colormap
            uint16 photometric;
            TIFFGetField(tiff, TIFFTAG_PHOTOMETRIC, &photometric);
            // read colormap
            uint16 *cmap_red = nullptr, *cmap_green = nullptr,
                   *cmap_blue = nullptr;
            int colormap_used = TIFFGetField(tiff, TIFFTAG_COLORMAP, &cmap_red,
                                             &cmap_green, &cmap_blue);
 
            auto* data = new float[imgWidth * imgHeight * 4];
            auto* pxl(new int[4]);
            for (int j = 0; j < imgHeight; ++j)
            {
                int lineindex = j * imgWidth;
                for (int i = 0; i < imgWidth; ++i)
                {  // scale intensities and set nodata values to white (i.e. the
                   // background colour)
                    unsigned pxl_idx(lineindex + i);
                    unsigned pos = 4 * (pxl_idx);
                    if (photometric == 1 && colormap_used == 1)
                    {
                        int idx = TIFFGetR(pixVal[pxl_idx]);
                        data[pos] = static_cast<float>(cmap_red[idx] >> 8);
                        data[pos + 1] =
                            static_cast<float>(cmap_green[idx] >> 8);
                        data[pos + 2] = static_cast<float>(cmap_blue[idx] >> 8);
                        data[pos + 3] = 1;
                    }
                    else
                    {
                        data[pos] =
                            static_cast<float>(TIFFGetR(pixVal[pxl_idx]));
                        data[pos + 1] =
                            static_cast<float>(TIFFGetG(pixVal[pxl_idx]));
                        data[pos + 2] =
                            static_cast<float>(TIFFGetB(pixVal[pxl_idx]));
                        data[pos + 3] =
                            static_cast<float>(TIFFGetA(pixVal[pxl_idx]));
                    }
                }
            }
            delete[] pxl;
 
            // set transparency values according to maximum pixel value
            if (photometric == 1)
            {
                float max_val(0);
                unsigned nPixels = 4 * imgWidth * imgHeight;
                for (unsigned j = 0; j < nPixels; ++j)
                {
                    if (data[j] > max_val)
                    {
                        max_val = data[j];
                    }
                }
 
                for (unsigned j = 0; j < nPixels; j += 4)
                {
                    data[j + 3] = max_val;
                }
            }
 
            vtkImageImport* image = vtkImageImport::New();
            image->SetDataOrigin(x0, y0, 0);
            image->SetDataSpacing(cellsize, cellsize, cellsize);
            image->SetWholeExtent(0, imgWidth - 1, 0, imgHeight - 1, 0, 0);
            image->SetDataExtent(0, imgWidth - 1, 0, imgHeight - 1, 0, 0);
            image->SetDataExtentToWholeExtent();
            image->SetDataScalarTypeToFloat();
            image->SetNumberOfScalarComponents(4);
            image->SetImportVoidPointer(data, 0);
            image->Update();
 
            _TIFFfree(pixVal);
            GTIFFree(geoTiff);
            XTIFFClose(tiff);
            return image;
        }
 
        XTIFFClose(tiff);
        ERR("VtkRaster::loadImageFromTIFF() - File not recognised as "
            "GeoTIFF-Image.");
        return nullptr;
    }
 
    ERR("VtkRaster::loadImageFromTIFF() - File not recognised as TIFF-Image.");
    return nullptr;
}

References ERR(), INFO(), uint32, and WARN().

Referenced by loadImage().

readWorldFile()

bool VtkRaster::readWorldFile ( std::string const & filename, vtkImageReader2 * image )

staticprivate

Tries to find and load the world file associated with a BMP/JPG/PNG-file and create a RasterHeader for the image.

Definition at line 350 of file VtkRaster.cpp.

{
    std::string const world_file = findWorldFile(filename);
    if (world_file.empty())
    {
        WARN("No world file found. Image is not georeferenced.");
        return false;
    }
 
    std::ifstream in(world_file.c_str());
    if (!in.is_open())
    {
        ERR("VtkRaster::readWorldFile(): Could not open file {:s}.", filename);
        return false;
    }
 
    std::string line;
    // x-scaling
    if (!std::getline(in, line))
    {
        return false;
    }
    double const delta_x = BaseLib::str2number<double>(line);
    // 2x rotation (ignored)
    if (!(std::getline(in, line) && std::getline(in, line)))
    {
        return false;
    }
    // negative y-scaling
    if (!std::getline(in, line))
    {
        return false;
    }
    double const delta_y = BaseLib::str2number<double>(line);
    if (delta_x != -delta_y)
        WARN(
            "Anisotropic pixel size detected ({:f} vs {:f}). An isotropic "
            "spacing of {:f} is assumed, be aware results may be wrong.",
            delta_x, delta_y, delta_x);
    // x-translation
    if (!std::getline(in, line))
    {
        return false;
    }
    double const x0 = BaseLib::str2number<double>(line);
    // y-translation
    if (!std::getline(in, line))
    {
        return false;
    }
    double const y0 = BaseLib::str2number<double>(line);
 
    int extent[3];
    image->GetOutput()->GetDimensions(extent);
    image->SetDataSpacing(delta_x, delta_x, delta_x);
    // for GIS the origin is on the lower left, for VTK it is on the upper left
    double const vtk_y0 = y0 + (extent[1] * delta_y);
    image->SetDataOrigin(x0, vtk_y0, 0);
    return true;
}

References ERR(), findWorldFile(), BaseLib::str2number(), and WARN().

Referenced by loadImageFromFile().

---

The documentation for this class was generated from the following files:

• Applications/DataExplorer/VtkVis/VtkRaster.h
• Applications/DataExplorer/VtkVis/VtkRaster.cpp