pyDEM-SRTM-example.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## pyDEM failure on a SRTM 30m DEM \n",
    "\n",
    "This is a minimal example to demonstrate a use case where slope and aspect calculations seem to fail. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import elevation\n",
    "import matplotlib.pyplot as plt\n",
    "import matplotlib\n",
    "import numpy as np\n",
    "from osgeo import gdal\n",
    "from pydem.dem_processing import DEMProcessor\n",
    "\n",
    "%matplotlib inline\n",
    "matplotlib.rcParams['figure.figsize'] = (10.0, 8.0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Using the `elevation` command line interface to get a DEM: "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "make: Nothing to be done for `download'.\n",
      "make: Nothing to be done for `all'.\n",
      "gdal_translate -q -co TILED=YES -co COMPRESS=DEFLATE -co ZLEVEL=9 -co PREDICTOR=2 -projwin -122.4 41.5 -122.1 41.2 SRTM1.vrt /Users/majo3748/Documents/earthlab/tutorials/Shasta-30m-DEM.tif\n"
     ]
    }
   ],
   "source": [
    "!eio clip -o Shasta-30m-DEM.tif --bounds -122.4 41.2 -122.1 41.5 "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Print projection information and verify WGS 84."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433],AUTHORITY[\"EPSG\",\"4326\"]]\n"
     ]
    }
   ],
   "source": [
    "filename = \"Shasta-30m-DEM.tif\"\n",
    "gdal_data = gdal.Open(filename)\n",
    "prj = gdal_data.GetProjection()\n",
    "print(prj)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now, computing slope and aspect with `pyDEM`:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "starting slope/direction calculation for chunk 1 [0:516, 0:516]\n"
     ]
    },
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "/Users/majo3748/anaconda/envs/py27/lib/python2.7/site-packages/pydem/dem_processing.py:563: MaskedArrayFutureWarning: setting an item on a masked array which has a shared mask will not copy the mask and also change the original mask array in the future.\n",
      "Check the NumPy 1.11 release notes for more information.\n",
      "  self.data[data.mask] = FILL_VALUE\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "Cannot cast ufunc add output from dtype('float64') to dtype('bool') with casting rule 'same_kind'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-4-9def4a7301a2>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0mprocessor\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mDEMProcessor\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfilename\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0mmag\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0maspect\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mprocessor\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mcalc_slopes_directions\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m/Users/majo3748/anaconda/envs/py27/lib/python2.7/site-packages/pydem/dem_processing.pyc\u001b[0m in \u001b[0;36mcalc_slopes_directions\u001b[0;34m(self, plotflag)\u001b[0m\n\u001b[1;32m    856\u001b[0m                                                    \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mdX\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mte\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0mbe\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    857\u001b[0m                                                    \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mdY\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mte\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0mbe\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mmag\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m--> 858\u001b[0;31m                                                    direction)\n\u001b[0m\u001b[1;32m    859\u001b[0m                     \u001b[0mdirection\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mflats\u001b[0m\u001b[0;34m]\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mFLAT_ID\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    860\u001b[0m                     \u001b[0mmag\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mflats\u001b[0m\u001b[0;34m]\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mFLAT_ID\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m/Users/majo3748/anaconda/envs/py27/lib/python2.7/site-packages/pydem/dem_processing.pyc\u001b[0m in \u001b[0;36m_find_flats_edges\u001b[0;34m(self, data, dX, dY, mag, direction)\u001b[0m\n\u001b[1;32m    939\u001b[0m                     \u001b[0mids_tmp2\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mdata\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mi_2\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mids_tmp\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mj_2\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mids_tmp\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m]\u001b[0m \u001b[0;34m==\u001b[0m \u001b[0melev_flat\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    940\u001b[0m                     \u001b[0mflats\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mi_2\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mids_tmp\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mids_tmp2\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mj_2\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mids_tmp\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mids_tmp2\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;31m\\\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m--> 941\u001b[0;31m                         \u001b[0;34m+=\u001b[0m \u001b[0mFLATS_KERNEL3\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0miii\u001b[0m\u001b[0;34m+\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mjjj\u001b[0m\u001b[0;34m+\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m    942\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    943\u001b[0m         \u001b[0;32mreturn\u001b[0m \u001b[0mflats\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mTypeError\u001b[0m: Cannot cast ufunc add output from dtype('float64') to dtype('bool') with casting rule 'same_kind'"
     ]
    }
   ],
   "source": [
    "processor = DEMProcessor(filename)\n",
    "mag, aspect = processor.calc_slopes_directions()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.imshow(np.log(mag), cmap=\"magma\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.imshow(aspect, cmap = \"viridis\")"
   ]
  }
 ],
 "metadata": {
  "anaconda-cloud": {},
  "kernelspec": {
   "display_name": "Python [py27]",
   "language": "python",
   "name": "Python [py27]"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 2
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython2",
   "version": "2.7.11"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 0
}

pyDEM-SRTM-fix.ipynb