svg and cmap coordinates seem inconsistent


I am facing an issue with generating a SVG output file and a related map file with the following dot file:

digraph "test" {
graph [rankdir=TB compound=true fontsize=10 fontname=Arial remincross=true start=self splines=true];
node [shape=rect height=0.7 margin=0.2 color=black fontsize=10 fontname=Arial];
edge [color=black fontsize=10 fontname=Arial];
layout=dot overlap=false;
0 [href=0 label=<Root Logical Function > height=0.2 style=filled fillcolor=lightgrey penwidth=3];

and with the following dot.exe command line attributes:
-Tsvg -Tcmapx_np -NURL=\\ ...

I am getting in SVG file :

So, on this simple example, how could I match the box of 197pt (or px ?) with a SVG viewpoint of 152pt ?

I guess there may be a relation between pt and px, but what is it ? And if so, Could I configure the command to get the same coordinates referential ?


I'm not sure why you are

I'm not sure why you are trying to combine bitmap and svg coordinates. If you could supply more details about that, there may be a simpler solution.
To address your question directly, pt (point) is a fixed unit, about 1/72 of an inch. This is the default unit in Graphviz and is used in SVG output. The px (pixel) unit is the size of a pixel and is thus display-dependent. For things like cmap output, Graphviz has to translate from points to pixels. It uses the dpi (pixels per inch) parameter, which by default is 96, but you can set it as you like. The margin and pad parameters can also cause a translation, though by default these are the same for cmap and SVG. To complicate things further, SVG output may well use the scale or translate attributes, so any coordinates you see need to be transformed by these.