http://www.sethoscope.net/heatmap/

mkdir -p ~/heatmap/tcx
mkdir ~/heatmap/tcx2gpx
cd ~/heatmap

curl http://www.nightwatch.org.uk/tcx2gpx/tcx2gpx > ~/heatmap/tcx2gpx/tcx2gpx
chmod +x ~/heatmap/tcx2gpx/tcx2gpx

git clone https://github.com/sethoscope/heatmap.git
git clone https://github.com/cbick/osmviz.git
ln -s ~/heatmap/osmviz/src/osmviz ~/heatmap/heatmap/osmviz

brew install ffmpeg
brew install python
brew install Homebrew/python/pillow

copy tcx files to ~/heatmap/tcx

cd ~/heatmap
~/heatmap/tcx2gpx/tcx2gpx -1 ~/heatmap/tcx/*

create a png file
start python directly from homebrew directory to make use of the the installed PIL module

cd ~/heatmap
/usr/local/bin/python heatmap/heatmap.py --decay 0.8 --height 800 --margin 10 -b black -o heatmap.png -g ~/heatmap/tcx2gpx.gpx -v
open heatmap.png

OpenStreetMap version

/usr/local/bin/python heatmap/heatmap.py --decay 0.8 --height 1200 --margin 10 -b black -o heatmap-osm.png -g ~/heatmap/tcx2gpx.gpx --osm -v
open heatmap-osm.png

create a animated heatmap

/usr/local/bin/python heatmap/heatmap.py --decay 0.8 --height 1200 --margin 10 -b black -o heatmap.mp4 -g ~/heatmap/tcx2gpx.gpx --animate --frequency=30 -v 
open heatmap.mp4