Advices on drawing a complex figure using tikz

How to convert image to tikz using inkscape

1. Open inkscape and import the image

2. Select the image and use Trace Bitmap...

3. For the image you posted I selected the following configuration:

4. The resulting vectorised version of your image:

If the lines are not smooth enough or too smooth, these parameters can be adjusted in the trace options.

At this point I would simply save the vector image as .pdf and use it with \includegraphics.

5. To convert the image to tikz, there exists and extension. [Be careful, the resulting file size may be huge]

Not a real answer - just a fake one to post this image, which was traced with potrace and polished a bit with inkscape

Dropbox link https://www.dropbox.com/sh/jk4wa9vcyeklqlg/AAAhva-i-pCASvhgLoI3v8Vba?dl=0

Edit: steps of the conversion

1. Opened with Gimp, converted to grayscale, and then to black/white using the "threshold" tool

2. Converted to pbm using imagemagick's convert (I assume Gimp could have done that, too)

3. Traced with potrace -s picture.pbm

4. Opened the svg file produced by potrace with inkscape and did a bit of manual tweaking of the contours.