geologyqgissymbology
I'm making a geological map using QGIS but I don't know how to draw a limestone lithology in QGIS.
To draw other lithologies I combine lines and dots in the best possible way but that is very limited.
Is there a fill pattern library that I can use to do this?
You can create pattern fill using different approach, as follows:
Create a new point grid shapefile using the tool
Vector -> Research tools -> Regular points
. 2. Select an input polygon file to get the extent, define grid spacing (1m in this example), and give name to output file.
rand( -180,180) in the expression beside the Angle, and 'Overlay' in layer blending:
Here is the output:
You can create a group to put inside both the polygon and point grid shapefile, so you can turn on/off the layers using the group.
Maybe it is not a perfect solution, but at least this approach will avoid lines intersection inside the group symbology within the same polygon shapefile layer.
Best Answer
I downloaded the USGS lithologic patterns from the Univeristy of Otago. At the same time, I installed inkscape software to work with these patterns.
Steps to use these patterns in QGIS: - Open USGS's patterns file in Inkscape -> Select the pattern you want to use -> File: export as a PNG image. I recommend a minimun size of 1125x900 (1500ppp). Don't forget to press 'Export'.
Before converting the PNG image to svg file, crop the borders using any image/photo editor. Otherwise, you will get as a fill pattern a grid of boxes containing the pattern. Now you have a PNG image, go to imagen.online-convert.com/es/convertir-a-svg and convert your png image to svg file. I don't know why but if you save your file as svg in Inkscape you can't use it in QGIS.
Now with your pattern as a svg file, open QGIS, go to 'Options' -> system -> add a new svg path to the folder where you saved your files. Accept. Select a polygon layer and select 'properties' -> style -> select a svg fill. Your folder should appear on the list. Select the pattern you want to use.
About the policy, USGS says that you just have to mention them: "Suggested citation U.S. Geological Survey, 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization (PostScript Implementation): U.S. Geological Survey Techniques and Methods 11-A2 [pubs.usgs.gov/tm/2006/11A02/]."