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 "cells": [
  {
   "cell_type": "markdown",
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   "source": [
    "# Heightmap Demo\n",
    "stough 202-\n",
    "\n",
    "In this quick demo I wanted to show how an image can be seen as a height-map, where the xy-plane is the domain of the image, while the z-axis represents the image intensity. This is easy enough with [matplotlib's 3D plotting](https://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html) capability. Specifically I would refer you to the examples [here](https://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html#surface-plots)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%matplotlib widget\n",
    "import matplotlib.pyplot as plt\n",
    "from matplotlib import cm\n",
    "from mpl_toolkits.mplot3d import Axes3D\n",
    "import numpy as np\n",
    "from skimage import color\n",
    "\n",
    "# For importing from alternative directory sources\n",
    "import sys  \n",
    "sys.path.insert(0, '../dip_utils')\n",
    "\n",
    "from matrix_utils import arr_info\n",
    "from vis_utils import vis_image"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "I = color.rgb2gray(plt.imread('../dip_pics/D_image.jpg'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "arr_info(I)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "vis_image(I, cmap='gray')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "X, Y = np.meshgrid(range(0,I.shape[0]), range(0,I.shape[1]), indexing='ij')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "fig = plt.figure(figsize=(5,5))\n",
    "ax = fig.add_subplot(111, projection='3d')\n",
    "\n",
    "ax.plot_surface(X, Y, I, cmap=cm.coolwarm);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The argument `projection='3d'` means the `ax` returned is a [Axes3D](https://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html) object. We then call that object's `plot_surface` method with a colormap so that the colors change as a function of the image intensity, or z coordinate. \n",
    "\n",
    "Note also that 3D plotting normalizes the units for a square output, even while the original image may not be. Lastly, code that does this surface plotting has been added to [vis_utils](../dip_utils/vis_utils.py) if we need it in the future."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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