Generate iplist file from Netbox for use with ipv4-heatmap project will which "Generate Hilbert curve heatmaps of the IPv4 address space."
./netbox-to-ipv4-heatmap.py  --help
usage: netbox-to-ipv4-heatmap.py [-h] -p PREFIX
optional arguments:
  -h, --help            show this help message and exit
  -p PREFIX, --prefix PREFIX
                        Prefix to search for in Netbox. ie 10.0.0.0/8
Create 'iplist' file from netbox:
./netbox-to-ipv4-heatmap.py -p 192.168.0.0/16 >/tmp/192.168.0.0-16.txt
Generate image using ipv4-heatmap and the iplist file:
./ipv4-heatmap -A 128 -B 8192 -y 192.168.0.0/16 -z 0 -o 192.168.png < /tmp/192.168.0.0-16.txt
Consider tweaking -A and -B values.
Example output from four different /16's:



