1

I'm creating a map of a camp facility (40 buildings) and have taken distance measurements and compass bearings. Now, I need to create the digital file, and had planned on using triangulation for accuracy. Is there an easy tool for me to use in Inkscape, to create a rigid link between two objects to control/limit their distance?

I can create a line (or rectangle) with exact dimensions, and use this as the measuring device between them. This method will involve a lot of pushing and pulling to rotate the three points into an accurate triangle.

Another option is to draw circles with the intended distance as the radius, then place objects on the intersecting points (old school compass use on paper maps!).

Here is a sample of my notes on the very rudimentary map:

enter image description here

Satellite imagery doesn't help much...too many trees and shadows.

Satellite

I'm open to using other open source tools.

  • I only visit the site once per year, so my measurements have already been collected this year. Last year, I took photographs to get the lay of the land. This is just a personal project (OCD!) so I have an updated map. I don't want to spend too much time on it, but I also want the time I invest to yield fruitful results. – dtphoto Jun 13 '18 at 15:58
  • So far, in Inkscape, creating building rectangles has been simple - 1 pixel = 1 foot. I can rotate the building to proper orientation...once. After that, I have to re-square it to the page, then correct back to the right degree rotation to match the compass bearing. Similarly, the lines I'm using to properly add space between buildings can be snapped to the first corner, but the second building doesn't seem to snap to the other end of the line. Rotating the line works fine, but then I'm looking at the hypotenuse across the rectangle's size, rather than the measured length or width. – dtphoto Jun 13 '18 at 16:02
1

I'm no longer much of a SketchUp user, but I suspect that you might be able to make that program work for you.

For genuine parametric modeling, which is what you are describing, another source would be Fusion 360, which is a free license for hobbyists (annual renewal required, still free) and allows for "locking down" measurements in the manner you've described.

For my final solution, I can also recommend Solvespace. It's also a 3D parametric modeling program, but is equally suited for 2D creation. I needed to construct what I later learned is a four-bar linkage and desired to construct it mathematically. That proved to be impossible but Solvespace allowed me to lock in certain dimensions and read the resulting calculations from other lines in the drawing.

Neither of the latter two programs is directly related to cartography, but I believe that one of them might provide the necessary results for your task.

Not to reject Inkscape completely, I did a search using "inkscape parametric" and discovered that someone has provided a minimal tutorial for using Inkscape for such tasks. It delves into editing the .svg file with a text editor, which I have not attempted, and cannot verify suitability.

I'm a fan of both Inkscape and Solvespace and would use both in concert with your project.

  • This is helpful. I've used Sketchup before. In this case, I only intended to make a 2D map...but that still may suffice with a top-down view. I had also begun to research editing the SVG. Although it seems like a lot of work, the entire project is, and that might actually be quicker! I don't know (yet) whether I can do relative/angular placement. – dtphoto Jun 13 '18 at 6:40
  • Solvespace will do angular placement, not sure about SU. – fred_dot_u Jun 13 '18 at 9:35
  • Solvespace is good it just needs a GUI ;) like emacs needs a decent editor. But then most cad apps have a solver like fusion, most of them a better one. Although autocad may be the worst choice it may be appropriate for the asker, it too has a solver. – joojaa Jun 13 '18 at 11:28
  • The version of solvespace I use has a GUI, all those icons on the left side control the creation and actions and constraints. Which version of solvespace has no GUI? – fred_dot_u Jun 13 '18 at 14:35
1

Your data probably is quite coarse and do not support the easiest possible calculations. A dream solution would be a program that could take all you have collected and solve the composition that fulfills all measurements.

I have done it in Excel. Its solver can be programmed to find a set of coordinates which conform with measured distances and bearings. Of course exact solution couldn't be found because there were plenty of extra measurements, but I programmed Solver to search the minimum of the sum of the squares of the errors.

You need an equation for every measured quantity as calculated from assumed coordinates and then you let Solver to find those coordinates that minimize the difference between calculated and measured quantities. Minimize = find the least squares solution.

If you have to find about 160 corners forget Excel.Even 16 points is a nightmare. Do it graphically as you thought.

You can keep all in good order with layers, line styles and colors. Inkscape allows you easily to draw lines and rotate them to bearings. As well you can draw circles with wanted center and radius. You can lock parts and still new objects snap to them, if you want it.

You want to find points. They can be

  • the ends of measured bearings and distances
  • crossings of circles
  • crossings of bearing lines
  • crossings of circles and bearing lines

Graphical work allows human reasoning in case of some radically contradicting measurements, which I believe to be found. Math solver would produce only a mess or nothing.

I believe all measurements are already done, you do not want to hear anything how the measurements should have been done for easy graphical work. If I happen to be wrong, please see some practical cartography guides from the era before GPS and total stations.

The best low cost tools that I have seen for this job, are

  • laser distance meter with optical aiming diopter
  • rectangular prism
  • precision compass for bearings
  • a big notebook of paper and a pen

Total stations and GPS are today the pro tools for the job, but they are probably unreachable for non-pro projects.

  • Yes, data is whatever I could get. The laser distance meter I had was good for 200', but in bright daylight and red/brown cabin walls didn't reflect the red laser very well, so that further restricted it to about 100 feet usable. Beyond that, I had a very basic compass...which was still sufficient (+/-10 degrees is OK). – dtphoto Jun 13 '18 at 15:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.