About MapAnalyst
Points in OpenStreetMap no longer appear at the correct location. They seem to have shifted.
MapAnalyst version 1.3.0 to 1.3.23 had a bug that resulted in wrong coordinates when exporting OpenStreetMap points. This bug was fixed in version 1.3.24, but OpenStreetMap points created with earlier versions of MapAnalyst will be offset in version 1.3.24 and later by a few kilometres when displayed in the OpenStreetMap in MapAnalyst. There is a new menu command to correct for this offset at Maps > Correct OpenStreetMap Misalignment. Note: only apply this correction once to your points, then save the project or export the points to a new file.
What is the influence of a map's projection on the analysis of its distortions?
MapAnalyst assumes that the old map and the new reference map use the same projection. If they do not share a common projection, visualizations will be overly distorted.
If the projection of the old map is known, the reference map should first be converted to this projection using a GIS, before the reference points are added.
If the projection of the old map is not known (which is often the case), an approximation of the projection can possibly be deduced by an analysis of the distortion pattern.
The projection does not play an important role and can often be ignored for maps at large and medium scale and/or for maps that are highly distorted.
See also the discussion on OpenStreetMap for more information on projections.
How can the distortion visualizations be displayed in the reference map?
Use Analyze > New Map. Also see Direction of Transformation for more on this.
How to best compare two or more old maps?
The recommended way is to compare each old map to a new reference map and to generate the visualizations in the coordinate system of the reference map (see Direction of Transformation for how to do this). You can then export the visualizations for each map and combine them in a GIS or a vector graphics software. This allows you to overlay the distortion visualizations of different maps.
Can I directly compare two old maps with MapAnalyst to find out whether one is a copy of the other?
Yes, although the recommended way is the one outlined above involving a GIS. Nevertheless, you can load an old map instead of a modern reference map on the right side of the MapAnalyst window. Control points can then be added and visualizations can be computed as with a modern reference map. However, the scale value and all distances computed or displayed are completely meaningless in such cases. A distortion grid or displacement vectors computed in this way, however, might be useful: if the grid has regularly sized cells, and the vectors are very short, one map is likely a copy of the other map (or both maps are a copy of a third one).
Can I georeference or register old maps with MapAnalyst?
With the current version of MapAnalyst it is not possible to resample old maps to register them with reference maps. This feature is currently under development and will be released with one of the next updates.
Is there a limit in the size of images that can be imported?
Scans of maps can be very large in terms of required memory. It is recommended that you down-sample your images to a maximum size of approximately 5000 by 5000 pixels. Large raster images might possibly slow down MapAnalyst, depending on the speed of your computer. The maximum possible size mainly depends on the amount of available memory.