intersectionlinear-referencingpointqgis-2symbology
I have lines representing curving streams and want to angle symbols at various points on the streams so that they are perpendicular to the angle in their particular locations.
What QGIS seems to do is give each point an angle that possibly represents the angle between the top and bottom of the stream. I've looked into writing an expression, but there doesn't seem to be a way to include degrees or angles as components.
I'm using the LRS plugin for these layers.
I think it's a bug, or more perhaps more worded more precisely: it's a result of inadequate user interface portrayal of the symbol properties and their effects. My deduction is that the same dialog box for point symbol properties is re-used, but not all the controls there are applicable for Simple Line Symbols.
It would help to also add an additional graphic showing what the desired final complete line will look like, even a pencil sketch. For example, are you really after a marker line, where every x distance has a symbol, or is it just arrows at the middle and/or ends?
For a true symbol marker line, you need to use Cartographic Representation, which requires Desktop Advanced license. If you're fortunate enough to have that, see how to get started with fix symbol rotation to page.
Rich man's (CartoRep) example: equally spaced fixed rotation marker symbol.
Poor man's repeated marker line symbol: it works, angle is fixed at 45deg to page according to symbol properties, but the distance between each point varies.
To round out the examples, for arrows at ends like you'd use to depict stream flow, see Line Properties >> Line Decorations and rotate to follow line. Here we've created a complex symbol, two arrow types on one line, by stacking lines (see "Layers" panel).
If I understand it correctly, you are trying to rotate symbols for point features. Rotating the point features themselves won't work. A point is a point, and has no direction. You should be able to perform symbol rotation through the layer's symbology tab, choose advanced and then rotation. You will need a field with rotation values for this in geographic or arithmetic degrees.
Best Answer
Not sure if this is what you're looking for, but if you use the
Marker lineSymbol layer type, you can set marker placement and rotation:The rotation field can be set by expression or field, and is relative to the angle of the line.
Please let me know if I've misinterpreted your question