Copying set of points perpendicular along polyline

Question

I have a polyline which represents the middle of a river. Perpendicular to this polyline there is a layer with a set of points. These points all have an "X" and "Y" coordinates as well as a height relative to sea level and represent the profile of the river.

However, these points are only present at one point. I want to copy this set of points to multiple locations along my polyline so that I can interpolate these points and get a DEM to load into a simulation programme that needs river cross-sections as input.

How to copy the point layer perpendicular along the polyline given a set interval (e.g. a meter between each set of points is sufficient)?

The points are lying on the same line, but I think the visualisation of QGIS makes it look like they are not.

Answer 1

So i started with a line which represents a river and a set of points with a certain "X","Y" and "Z" coördinate, which represents the profile of the river. Every points also contains information on the distance between the first point (most northern point in this case) and the point itself.

1. First i measured the distance from the line to the first point with the measure line tool and created a parallel through the first point. This causes some discrepancy, because the measure line tool is not comepletly exact, but for my problem this does not really matter
2. From the created parallel, I used offset lines to create a parallel through each point

3. Then I manually added a "Z" coördinate to each line, used densify by interval to create more vertices and lines to points to create a raster of points.

4. Lastly i used Natural neighbour to create a grid that represents my river, which is shown below.

This solution does currently work for me as my project area is not that large, but in the future the project area will become larger and this will take a lot of time. Therefore, I am still interested in a more convenient solution.