Image by Víctor Olaya \"Sistemas de Información Geográfica\", CC-BY
" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "skip" } }, "source": [ "Another example:\n", "\n", "\n", "more info about rasters vs vectors:\n", "http://vector-conversions.com/vectorizing/raster_vs_vector.html" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "## Vector data\n", "\n", "* **Entities**: Points, Lines and Polygons\n", "* **Common formats**: ESRI Shapefiles, GeoJSON, TopoJSON, ...\n", "\n", "\n", "\n", "Image by M. W. Toews https://en.wikipedia.org/wiki/File:Simple_vector_map.svg, CC-BY
" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "## Raster data\n", "\n", "* **Common formats**: GeoTIFF, JPEG2000, SRTM3, ... \n", "\n", "" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "# GEO referenced \n", "\n", "* Vectors and Rasters can exist in fields other than GIS.\n", "* The are part of a GIS when they are Geo-Referenced.\n", "* For example: \n", " * A *Polygon* is Geo-Referenced when you know how to draw it on earth\n", " * A *Raster* is Geo-Referenced when you know where is the raster located " ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "## Projections\n", "\n", "A method to locate points on earth\n", "\n", "TL;DR: A mess.\n", "\n", "* The Earth is approximately a sphere, which is not a [developable surface](https://en.wikipedia.org/wiki/Developable_surface) (i.e. _it cannot be flattened onto a plane without distortion_)\n", "* Therefore, we need _projections_ that attempt to represent the Earth on a plane, with various tradeoffs and limitations\n", "\n", "" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "# 2. ~~Why yet another~~ Existing software\n", "\n", "The landscape is complicated and somewhat difficult to navigate at times:\n", "\n", "" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "Summary of key libraries:\n", "\n", "| Python | | C/C++ |\n", "|----------|---|--------|\n", "| pyproj | ⇒ | PROJ.4 |\n", "| Fiona | ⇒ | OGR |\n", "| Shapely | ⇒ | GEOS |\n", "| rasterio | ⇒ | GDAL |" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "# 3. telluric library\n", "\n", "_telluric is an open source (MIT) Python library to manage vector and raster geospatial data in an interactive and easy way._\n", "\n", "* Projection-aware geometric operations\n", "* Simple I/O for raster and vector data\n", "* Interactive visualization\n", "* 🕮 Documentation http://telluric.readthedocs.io/\n", "* 🔧 Source https://github.com/satellogic/telluric" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "Importing for interactive use is short:" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "slideshow": { "slide_type": "fragment" } }, "outputs": [], "source": [ "import telluric as tl\n", "from telluric.constants import WGS84_CRS, WEB_MERCATOR_CRS" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "Basic geometry definition using `GeoVector`: in the simplest case, the bounds and the projection (CRS)" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "slideshow": { "slide_type": "fragment" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "GeoVector(shape=POLYGON ((34.6 32, 34.6 32.3, 35 32.3, 35 32, 34.6 32)), crs=CRS({'init': 'epsg:4326'}))\n" ] } ], "source": [ "gush_dan = tl.GeoVector.from_bounds(\n", " xmin=34.6, ymin=32, xmax=35.0, ymax=32.3, crs=WGS84_CRS\n", ")\n", "print(gush_dan)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "### We added extra attention to Jupyter noteobook visualization, checkout this plot " ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "slideshow": { "slide_type": "fragment" } }, "outputs": [ { "name": "stderr", "output_type": "stream", "text": [ "/home/guyd/pEnvs/telluric-dev/local/lib/python3.5/site-packages/telluric/plotting.py:141: UserWarning: Plotting a limited representation of the data, use the .plot() method for further customization\n", " \"Plotting a limited representation of the data, use the .plot() method for further customization\")\n" ] }, { "data": { "image/svg+xml": [ "" ], "text/html": [ "