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NV5 Geospatial Blog

Each month, NV5 Geospatial posts new blog content across a variety of categories. Browse our latest posts below to learn about important geospatial information or use the search bar to find a specific topic or author. Stay informed of the latest blog posts, events, and technologies by joining our email list!



NV5 at ESA’s Living Planet Symposium 2025

NV5 at ESA’s Living Planet Symposium 2025

9/16/2025

We recently presented three cutting-edge research posters at the ESA Living Planet Symposium 2025 in Vienna, showcasing how NV5 technology and the ENVI® Ecosystem support innovation across ocean monitoring, mineral exploration, and disaster management. Explore each topic below and access the full posters to learn... Read More >

Monitor, Measure & Mitigate: Integrated Solutions for Geohazard Risk

Monitor, Measure & Mitigate: Integrated Solutions for Geohazard Risk

9/8/2025

Geohazards such as slope instability, erosion, settlement, or seepage pose ongoing risks to critical infrastructure. Roads, railways, pipelines, and utility corridors are especially vulnerable to these natural and human-influenced processes, which can evolve silently until sudden failure occurs. Traditional ground surveys provide only periodic... Read More >

Geo Sessions 2025: Geospatial Vision Beyond the Map

Geo Sessions 2025: Geospatial Vision Beyond the Map

8/5/2025

Lidar, SAR, and Spectral: Geospatial Innovation on the Horizon Last year, Geo Sessions brought together over 5,300 registrants from 159 countries, with attendees representing education, government agencies, consulting, and top geospatial companies like Esri, NOAA, Airbus, Planet, and USGS. At this year's Geo Sessions, NV5 is... Read More >

Not All Supernovae Are Created Equal: Rethinking the Universe’s Measuring Tools

Not All Supernovae Are Created Equal: Rethinking the Universe’s Measuring Tools

6/3/2025

Rethinking the Reliability of Type 1a Supernovae   How do astronomers measure the universe? It all starts with distance. From gauging the size of a galaxy to calculating how fast the universe is expanding, measuring cosmic distances is essential to understanding everything in the sky. For nearby stars, astronomers use... Read More >

Using LLMs To Research Remote Sensing Software: Helpful, but Incomplete

Using LLMs To Research Remote Sensing Software: Helpful, but Incomplete

5/26/2025

Whether you’re new to remote sensing or a seasoned expert, there is no doubt that large language models (LLMs) like OpenAI’s ChatGPT or Google’s Gemini can be incredibly useful in many aspects of research. From exploring the electromagnetic spectrum to creating object detection models using the latest deep learning... Read More >

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Dynamic Plots Using an Equation String

Anonym

The PLOT function's new Equation argument adds flexibility to the creation of plots in IDL, allowing you to create dynamic, interactive output.

The Equation argument on the PLOT function allows you to specify either a string containing an equation with variable X, or the name of an IDL function that accepts X as an input argument. The result of the equation (or the function) should be a one-dimensional array of Y coordinates to be plotted.

  • If Equation is an expression, then the EXECUTE function is called once with the X array. Note that in certain circumstances (such as the IDL Virtual Machine), you may not be able to use the EXECUTE function.
  • If Equation is a function name, then CALL_FUNCTION is called once, with the X array as an input argument. The function should return a one-dimensional result array.

Once IDL creates the plot output, if you then interactively adjust the plot range, IDL will automatically recompute the equation to cover the new range.

We'll use the BESELJ function in IDL to show how to use a Function String in the Equation Argument:

 

; Plot J Bessel Functions

pj0 = PLOT('BESELJ(X, 0)', XRANGE=[0.0, 50],  $

  XTITLE='X', YTITLE='$J_n(x)$ or $Y_n(x)$', $

  TITLE='J Bessel Function')

pj1 = PLOT('BESELJ(X, 1)', 'r2', XRANGE=[0.0, 50], /OVERPLOT)

pj2 = PLOT('BESELJ(X, 2)', 'b2', XRANGE=[0.0, 50], /OVERPLOT)

; Annotate the plot.

xcoords = [1, 1.66, 3]

ycoords = [.8, .62,.52]

labels = '$\it' + ['J_0','J_1','J_2'] + '$'

  t = TEXT(xcoords, ycoords, labels, /DATA)

 

If you run the code above, it should generate a graphic like this:

Once IDL creates the plot, test out its dynamic capabilities:

  • Try clicking with the middle mouse button on the graphic and panning around.
  • You can also use the mouse wheel to zoom in or out, or hold down the <Shift> key and draw a zoom box.
  • Change the plot range programatically at the IDL command line:

pj0.xrange=[0.0, 150]

As you change the plot range, IDL recomputes the equation with new X values that span the new range.

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