Planet Zoo Heightmap Guide

I already made the calculations required for the custom heightmap function!

A planet Zoo Sandbox Map is roughly 1 km² big (1000 x 990 m). The Heightmap is required to be a 1024 x 1024 pixels tif file. This equals to 0.98 m/pixel. So: One pixel in the heightmap translates to 1 m on your map. But be aware, that the resolution of this feauture is limited. My tests show, that the game can only create reasonable structures from 2×2 pixels upwards.

Now to the height: The standard colour (flat with the entrance) is RGB 128 (red, blue and green all set to 128). I calculated, that 1 colour value translates to one meter in height (roughly, in my test I tested up to 128 m where I got a deviation of 0.5 meter). The darker the colour, the deeper it gets, the lighter the higher:
RGB-value Height deviation
98: -30 m
118: -10 m
128: 0 m
138: +10 m
148: +20 m
256: +128 m

The entrance will be placed at the bottom line of the heightmap in the middle.

I hope, that this guide was helpful to you

You need a image manipulation program like Photoshop, MS paint or (what I recommend) paint.net (freeware).
You can create a 1024×1024 pixel template and colour it in greyscale.
You have to export your file as .tif
and copy it into your Planet Zoo Folder Documents > Frontier Developments > Planet Zoo > UserHeightmaps
Then, your custom heightmap will appear in the map creation menu.

Go to https://cs.heightmap.skydark.pl/ and select your zoos map location, the blue square will contain your zoo map. Go to the settings (i in the top left) and tick the box with “draw grid”. We need this to select the right location in the image manipulation program. Also make a screenshot of the map zoomed in on the blue square.
Download the heightmap as .png. Cut out the middle square of the heightmap and cut out the blue square from the screenshot. Open the cut out map from the screenshot in another layer above the cut out heightmap and resize it so that it fits to the low resolution of the heightmap. Choose any 62×62 pixels area on the map (this refers to 1×1 km in the world map, which fits to the planet zoo sandbox map), you want your zoo to be and cut the file to this square. Resize the file to 1024×1024 pixels. Choose a point in your heightmap that should be your ground level and adjust the brightness so, that the colour of this pixel becomes RGB 128 (If the colour was RGB 108 increase the brightness by 20). If you want any elevations, or lowering (like lakes) take a brush and paint the area in the desired RGB colour. Save the file as .tif and move it to the directory.The resolution is not great, but it is totally playable, you can smooth out the edges in planet zoo, or soften the edges in your image manipulation program.