Convert QGIS Map to TIFF File

qgis-map-to-tiff.md

Convert QGIS Map to TIFF File

Using QgsMapRendererParallelJob

1. Iterate over shape files in INPUT_FOLDER
2. Apply style file
3. Generate TIFF file using QgsMapRendererParallelJob

import os
from pathlib import Path

from qgis.core import (
    QgsMapSettings,
    QgsCoordinateReferenceSystem,
    QgsMapRendererParallelJob,
    QgsVectorLayer,
)

from qgis.PyQt.QtGui import QColor
from qgis.PyQt.QtCore import QSize


INPUT_FOLDER = r"D:\projects\playground\python\data"
OUTPUT_FOLDER = r"D:\projects\playground\python\results"

STYLE_FILE = r"D:\projects\playground\python\contours.qml"

EPSG_CODE = 2961
CRS = QgsCoordinateReferenceSystem(EPSG_CODE)

BACKGROUND_COLOR = QColor(255, 255, 255)
OUTPUT_SIZE = QSize(2000, 1500)
OUTPUT_DPI = 96


def finished(render, output_file_path):
    image = render.renderedImage()
    image.save(output_file_path)


def process_shapefile(file):
    
    output_file_name = f"{file.stem}.tiff"
    output_file_path = os.path.join(OUTPUT_FOLDER, output_file_name)

    layer = QgsVectorLayer(str(file), output_file_name, "ogr")
    layer.loadNamedStyle(STYLE_FILE)

    settings = QgsMapSettings()
    settings.setLayers([layer])
    settings.setDestinationCrs(CRS)
    settings.setBackgroundColor(BACKGROUND_COLOR)
    settings.setOutputSize(OUTPUT_SIZE)
    settings.setOutputDpi(OUTPUT_DPI)
    # settings.setFlag(QgsMapSettings.Antialiasing, True)
    settings.setExtent(layer.extent())

    render = QgsMapRendererParallelJob(settings)
    
    render.finished.connect(lambda: finished(render, output_file_path))
    render.start()


for file in Path(INPUT_FOLDER).glob("*.shp"):
    process_shapefile(file)

Notes

• output size and DPI may have to be adjusted depending on the vector layer's extent
• does not create a world file

Using QgsLayoutExporter

1. Iterate over shape files in INPUT_FOLDER
2. Apply style file
3. Create (temporary) layout
4. Generate TIFF file with world file using QgsLayoutExporter

import os
from pathlib import Path

from qgis.core import (
    QgsCoordinateReferenceSystem,
    QgsVectorLayer,
    QgsProject,
    QgsPrintLayout,
    QgsLayoutItemMap,
    QgsLayoutSize,
    QgsUnitTypes,
    QgsLayoutExporter,
)

from qgis.PyQt.QtGui import QColor
from qgis.PyQt.QtCore import QSize


INPUT_FOLDER = r"D:\projects\playground\python\data"
OUTPUT_FOLDER = r"D:\projects\playground\python\results"

STYLE_FILE = r"D:\projects\playground\python\contours.qml"

# EPSG_CODE = 2961
# CRS = QgsCoordinateReferenceSystem(EPSG_CODE)

OUTPUT_SIZE = QSize(2000, 1500)
OUTPUT_DPI = 150


def process_shapefile(file):
    
    output_file_name = f"{file.stem}.tiff"
    output_file_path = os.path.join(OUTPUT_FOLDER, output_file_name)
    
    layer = QgsVectorLayer(str(file), output_file_name, "ogr")
    layer.loadNamedStyle(STYLE_FILE)

    project = QgsProject.instance()
    layout = QgsPrintLayout(project)
    layout.initializeDefaults()

    # A4
    # page = layout.pageCollection().page(0)
    # map = QgsLayoutItemMap(layout)
    # map.attemptResize(page.pageSize())
    
    # size 20 cm x 20 cm
    size = QgsLayoutSize(200, 200, QgsUnitTypes.LayoutMillimeters)
    layout.pageCollection().page(0).setPageSize(size)
    map = QgsLayoutItemMap(layout)
    map.attemptResize(size)

    map.setLayers([layer])
    map.zoomToExtent(layer.extent())
    layout.addLayoutItem(map)

    settings = QgsLayoutExporter.ImageExportSettings()
    settings.dpi = OUTPUT_DPI
    settings.imageSize = OUTPUT_SIZE
    settings.generateWorldFile = True

    exporter = QgsLayoutExporter(layout)
    exporter.exportToImage(output_file_path, settings)
    

for file in Path(INPUT_FOLDER).glob("*.shp"):
    process_shapefile(file)

Notes

• output size and DPI may have to be adjusted depending on the vector layer's extent
• allows to create a world file