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fermigas edited this page Oct 14, 2018 · 15 revisions

Lunar Terminator Visualization Tool

October 2018 Update

(click here to skip to the original home page's content)

Welcome to a fork of the LTVT wiki. LTVT lost their home when wikispaces shut down, as did several other terrific websites (LPOD The Moon Wiki). Luckily, they are back up and we're trying here to get the LTVT site on its feet.

This isn't the official site, but the original author Jim Mosher was kind enough to provide permission and a huge archive of files (through John Moore on Cloudy Nights):

"None of this was ever intended to be proprietary, so anyone who would like to is welcome to post it wherever they like, and do with it whatever they like." Jim Mosher

So we took him up on it. was preserved as HTML pages. These have all been converted to github markdown. All the images on the original site have been uploaded to this github wiki. Nonetheless, you'll likely see links that don't work and images that aren't loading. As long as you're reading this sentence we're working on it. WIKI TODO and Done List and How To Contribute

If you want to get the program or code the LTVT Program Downloads page has you covered.

Many resources that can enrich your use of the the program can be found here Downloads.

If you want to learn how to use LTVT, you can hardly do better than LTVT-function-details.

Source code can be obtained here: Github LTVT Repository. You can find the source code for older versions by choosing its branch in the link above or by following links from the Source Code Archive which contains zipped versions of older source code.

Here's the Original Home Page Content, which you can also find on the Wayback Machine

Lunar Terminator Visualization Tool

Table of Contents


The Lunar Terminator Visualization Tool (LTVT) is a free software tool for the intermediate to advanced student of lunar topography. It permits Moon images in a variety of formats to be located, viewed and compared with a uniform set of tools. It also permits highly accurate measurements to be made on those images.

Design Goals

  • Accuracy
  • Configurable and expandable by end user
  • Ease of use


  • Displays orthographic views of the Moon from any user-selected angle
  • Can paint the lunar sphere with a variety of user-supplied imagery:
    • Texture files covering the whole, or a part of, the Moon in simple cylindrical projection
    • Maps in Mercator (e.g., equatorial LAC's), Transverse Mercator (e.g., LTO's) and Lambert (e.g., high latitude LAC's)
    • Any actual photo taken from Earth or space, provided the date, time and camera location are known
  • With optional digital elevation model (DEM) data, can paint the sphere with simulations of the expected pattern of light and shadow for any combination of viewing and lighting angles; including correct projection of the three-dimensional locations of the surface objects.
  • On the painted sphere, can overlay on the dots encoding information specific to particular longitudes and latitudes, including:
    • Nomenclature
    • Point elevations
    • Features of special interest
  • Dot files available for complete current IAU nomenclature and major selenodetic control systems.
  • Accurately plots the theoretical terminator position based on a user-supplied sub-solar point.
  • Interactively displays the sun angle as the mouse is moved over the image.
  • Can accurately compute the viewing and lighting geometry for any date from 1601-xxxx using optional JPL ephemeris files.
  • Infinite zoom capability
  • An unlimited number of instances of the program can be run simultaneously for overlay of images from different sources (similar to Photoshop "layers")
  • Using the optional JPL ephemeris files, can predict past or future times when the terminator will be at a particular location relative to the surface features, based either on solar colongitude or on the sun angle at a particular feature.
  • Can similarly tabulate past and future times when a given surface feature will be seen at a given distance from the disk center (due to varying librations).
  • List of calibrated photos permanently stored on disk. List can be interrogated to automatically locate and display all calibrated photos showing a particular feature, ranked by sun angle.
  • Can also search a list of dates and times of uncalibrated photos to locate ones that could potentially show a given feature with a particular lighting (if it happens to fall with the photo's field).
  • Tools for:
    • Altering Gamma of displayed texture/image.
    • Identifying nearest feature in current dot file.
    • Measuring distances and bearings in kilometers and degrees.
    • Determining surface height differences based on the observed starting and ending points of solar shadows.
    • Determining expected limit of visibility (theoretical limb circle) for a given sub-Earth point.
    • Interactively drawing circles for accurately estimating (and optionally recording) the positions and diameters of circular features.
    • Counting number of displayed dots.
    • Saving annotated version of current screen display.

System Requirements

  • LTVT works only on Windows-compatible PC's
  • It displays best using the "Windows Classic" desktop theme (simple window borders)

Additional Information

This page has been edited 12 times. The last modification was made by - JimMosher JimMosher on Jan 8, 2010 10:59 am

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