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<section class="sphx-glr-example-title" id="display-an-isocurve">
<span id="sphx-glr-gallery-scene-isocurve-py"></span><h1>Display an Isocurve<a class="headerlink" href="#display-an-isocurve" title="Link to this heading">#</a></h1>
<p>Simple use of SceneCanvas to display an Isocurve visual.</p>
<img src="../../_images/sphx_glr_isocurve_001.png" srcset="../../_images/sphx_glr_isocurve_001.png" alt="isocurve" class = "sphx-glr-single-img"/><div class="highlight-Python notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">sys</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">vispy</span><span class="w"> </span><span class="kn">import</span> <span class="n">app</span><span class="p">,</span> <span class="n">scene</span><span class="p">,</span> <span class="n">visuals</span>
<span class="kn">from</span><span class="w"> </span><span class="nn">vispy.util.filter</span><span class="w"> </span><span class="kn">import</span> <span class="n">gaussian_filter</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">numpy</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="nn">np</span>
<span class="n">canvas</span> <span class="o">=</span> <span class="n">scene</span><span class="o">.</span><span class="n">SceneCanvas</span><span class="p">(</span><span class="n">keys</span><span class="o">=</span><span class="s1">'interactive'</span><span class="p">,</span> <span class="n">title</span><span class="o">=</span><span class="s1">'Isocurve(s) overlayed '</span>
<span class="s1">'over Random Image Example'</span><span class="p">)</span>
<span class="n">canvas</span><span class="o">.</span><span class="n">size</span> <span class="o">=</span> <span class="mi">800</span><span class="p">,</span> <span class="mi">600</span>
<span class="n">canvas</span><span class="o">.</span><span class="n">show</span><span class="p">()</span>
<span class="c1"># Set up a viewbox to display the image with interactive pan/zoom</span>
<span class="n">view</span> <span class="o">=</span> <span class="n">canvas</span><span class="o">.</span><span class="n">central_widget</span><span class="o">.</span><span class="n">add_view</span><span class="p">()</span>
<span class="c1"># Create the image</span>
<a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">img_data</span></a> <span class="o">=</span> <a href="https://numpy.org/doc/stable/reference/generated/numpy.empty.html#numpy.empty" title="numpy.empty" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-function"><span class="n">np</span><span class="o">.</span><span class="n">empty</span></a><span class="p">((</span><span class="mi">200</span><span class="p">,</span> <span class="mi">100</span><span class="p">,</span> <span class="mi">3</span><span class="p">),</span> <span class="n">dtype</span><span class="o">=</span><a href="https://numpy.org/doc/stable/reference/arrays.scalars.html#numpy.uint8" title="numpy.uint8" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-attribute"><span class="n">np</span><span class="o">.</span><span class="n">ubyte</span></a><span class="p">)</span>
<a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">noise</span></a> <span class="o">=</span> <a href="https://numpy.org/doc/stable/reference/random/generated/numpy.random.normal.html#numpy.random.normal" title="numpy.random.normal" class="sphx-glr-backref-module-numpy-random sphx-glr-backref-type-py-function"><span class="n">np</span><span class="o">.</span><span class="n">random</span><span class="o">.</span><span class="n">normal</span></a><span class="p">(</span><span class="n">size</span><span class="o">=</span><span class="p">(</span><span class="mi">200</span><span class="p">,</span> <span class="mi">100</span><span class="p">),</span> <span class="n">loc</span><span class="o">=</span><span class="mi">50</span><span class="p">,</span> <span class="n">scale</span><span class="o">=</span><span class="mi">150</span><span class="p">)</span>
<a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">noise</span></a> <span class="o">=</span> <span class="n">gaussian_filter</span><span class="p">(</span><a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">noise</span></a><span class="p">,</span> <span class="p">(</span><span class="mi">4</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">0</span><span class="p">))</span>
<a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">img_data</span></a><span class="p">[:]</span> <span class="o">=</span> <a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">noise</span></a><span class="p">[</span><span class="o">...</span><span class="p">,</span> <a href="https://numpy.org/doc/stable/reference/constants.html#numpy.newaxis" title="numpy.newaxis" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-data"><span class="n">np</span><span class="o">.</span><span class="n">newaxis</span></a><span class="p">]</span>
<span class="n">image</span> <span class="o">=</span> <span class="n">scene</span><span class="o">.</span><span class="n">visuals</span><span class="o">.</span><span class="n">Image</span><span class="p">(</span><a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">img_data</span></a><span class="p">,</span> <span class="n">parent</span><span class="o">=</span><span class="n">view</span><span class="o">.</span><span class="n">scene</span><span class="p">)</span>
<span class="c1"># move image behind curves</span>
<span class="n">image</span><span class="o">.</span><span class="n">transform</span> <span class="o">=</span> <span class="n">visuals</span><span class="o">.</span><span class="n">transforms</span><span class="o">.</span><span class="n">STTransform</span><span class="p">(</span><span class="n">translate</span><span class="o">=</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">))</span>
<span class="c1"># level and color setup</span>
<a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">levels</span></a> <span class="o">=</span> <span class="p">[</span><span class="mi">40</span><span class="p">,</span> <span class="mi">50</span><span class="p">,</span> <span class="mi">60</span><span class="p">]</span>
<a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">color_lev</span></a> <span class="o">=</span> <span class="p">[(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span>
<span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span>
<span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">)]</span>
<span class="c1"># Create isocurve, make a child of the image to ensure the two are always</span>
<span class="c1"># aligned.</span>
<span class="n">curve</span> <span class="o">=</span> <span class="n">scene</span><span class="o">.</span><span class="n">visuals</span><span class="o">.</span><span class="n">Isocurve</span><span class="p">(</span><a href="https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">noise</span></a><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">levels</span></a><span class="o">=</span><a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">levels</span></a><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">color_lev</span></a><span class="o">=</span><a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">color_lev</span></a><span class="p">,</span>
<span class="n">parent</span><span class="o">=</span><span class="n">view</span><span class="o">.</span><span class="n">scene</span><span class="p">)</span>
<span class="c1"># Set 2D camera</span>
<span class="n">view</span><span class="o">.</span><span class="n">camera</span> <span class="o">=</span> <span class="n">scene</span><span class="o">.</span><span class="n">PanZoomCamera</span><span class="p">(</span><span class="n">aspect</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span>
<span class="c1"># the camera will scale to the contents in the scene</span>
<span class="n">view</span><span class="o">.</span><span class="n">camera</span><span class="o">.</span><span class="n">set_range</span><span class="p">()</span>
<span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s1">'__main__'</span> <span class="ow">and</span> <a href="https://docs.python.org/3/library/functions.html#int" title="builtins.int" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">sys</span><span class="o">.</span><span class="n">flags</span><span class="o">.</span><span class="n">interactive</span></a> <span class="o">==</span> <span class="mi">0</span><span class="p">:</span>
<span class="n">app</span><span class="o">.</span><span class="n">run</span><span class="p">()</span>
</pre></div>
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