However, the original DEM data file uses a Plate Carrée projection. And finally I used a Plate Carrée projection for constellation charts, because the perpendicular gridlines make it easy to read coordinates (which are essential for finding stars that rise and set throughout the night).Ĭhanging the Map Projection of a DEM File: In this project I wanted to use an orthographic projection to show each hemisphere of the planet (North, South, East and West). I used an Orthographic projection for these topographic maps to visualize what planets look like from outer space. For example, Eckert IV preserves area measurements, so I used Eckert IV in geologic maps to show how much area on the planet was made up of each geological formation. The choice of projection depends on the purpose of the map. All map projections distort space, but you can see that the effects are quite different depending on the projection: To visually compare these different map projections, you can use a Tissot's indicatrix - a set of circles of the same size plotted at different places on the globe. There are many different projections, and for the maps in the Atlas of Space series I used Eckert IV, Orthographic, and Plate Carrée projections. To map a 3D object in 2D space, the surface must be transformed using a map projection.
#Atlas of moons software
Note: Many software programs can't read this kind of file, so it's normal if the downloaded DEM looks strange in Preview or other default image applications.Ī Quick Introduction: Before we get into the details of map projection transformations, here's a quick overview of what this actually means.
#Atlas of moons code
To run the code in this tutorial, you will need to download one of the DEM files linked above. GeoTIFF files also have embedded geographic data that allows tools like GDAL to correctly position the elevation data onto a globe.
Each pixel in these GeoTIFF files describes the elevation at that specific location on the planet. For this project I'm using the United States Geologic Survey's DEMs for Mars, Mercury, Venus, and the Earth's Moon.
Map design in Illustrator and Photoshopĭigital Elevation Models (DEMs) are data files that provide height information.There is no perfect software that fits everyone's needs, so you'll want to understand the pros and cons for the different raster and vector programs before choosing. I use Adobe Photoshop and Illustrator, but you can also use the free open-source programs Gimp and Inkscape. You'll need software for editing raster and vector images ( this article explains the difference). The installation instructions in the Conda section are probably the most relevant if you've installed Python as described above.
#Atlas of moons install
For the code in this repository you will also need to install GDAL. After you've installed Python using these tutorials, you can use Git Desktop and the instructions in this tutorial to download the code and data in this tutorial. Software Carpentry has great tutorials for installing Python (scroll down and follow the directions in the Bash Shell and Python sections), getting starting with Jupyter Notebooks, and beginner-friendly Python programming. Special instructions for beginners If you're new to coding: Dependencies can be installed with pip install -r requirements.txt. Python dependencies: matplotlib numpy pandas os cartopy json osgeo math scipy jupyter. If you have comments or suggestions for this tutorial, please let me know on my blog! You can also buy these topographic maps for Mars, Venus, Mercury, and the Moon. Software used includes Python 3.7.1, GDAL 2.4.1, Illustrator CC 2019 and Photoshop CC 2019.
#Atlas of moons how to
This repository explains how to make topographic maps of planets and moons using open-source data from the USGS, IAU, and NASA.
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