By Sam Bain

Leapfrog allows users to import a range of images into a project so they can be viewed on topography. These include but are not limited to topographic maps, satellite imagery, aerial photos, and geological maps.

Imported images can be viewed projected on topography by adding the topography to the scene and then selecting them from the GIS data drop-down box below the topography object in the shape list (Figure 1).

The custom view option (selectable in the GIS data drop-down menu) allows a user to create and save a particular combination of GIS data projected on topography. GIS data such as polylines and polygons can be added to a custom view, along with multiple GIS images or maps (Figure 2). This allows the creation and saving of a scene showing the important GIS data, allowing the user to quickly display the same view again in the future.

Figure 1: Satellite imagery of the Canterbury region superimposed on the local topography. The red box highlights the drop down menu for GIS data.
Figure 1: Satellite imagery of the Canterbury region superimposed on the local topography. The red box highlights the drop down menu for GIS data.

The example shown in Figure 2 combines the same regional satellite image as in Figure 1 with two topographic maps of Christchurch City. The “Edit GIS view” dialog displays a list of available layers and the currently used layers. The order of preference is controlled by each layers position in the current layers list.

For interest, the on-going but diminishing Christchurch earthquake sequence is shown below the topography (Figure 2). Points represent single earthquakes, and their diameter is proportional to the earthquake magnitude. It has certainly been a shaky time here over the last few years!

There are many situations in which projecting multiple images on one topography might be useful. Combining aerial and satellite imagery with geological maps in the one scene aids the assessment of how surficial features relate to the underlying geology. A proposed mine area may be covered by multiple geological maps and it can be helpful to compare these in a 3D environment alongside topography. Multiple maps may be added to a view but one given a lower transparency. This allows direct comparison of the different interpretations.

This feature is available in the Leapfrog GeoLeapfrog Hydro, and Leapfrog Geothermal products. A step-by-step tutorial for creating a custom scene is available in the Leapfrog help menu inside each product.

Figure 2
Figure 2

Figure 2: Satellite imagery and regional map projected on the same topography as shown earlier. The ongoing Christchurch earthquake sequence is also shown in the scene, with earthquakes coloured by magnitude (MM >6 are red , MM 5 to 6 are green, and MM <5 are black). Earthquake data was downloaded from GNS Science National Earthquake Information Database.

3 thoughts on “Viewing multiple images projected on topography”

  1. Nice feature! In the example shown on figure 2, am i correct in understanding that the topographic map appears as an “inset” within the satellite imagery simply because that was the extent of the topographic map images?
    If the topographic map was the same size/coverage as the satellite map, the scenario in figure 2 could not be achieved, correct? Or did I miss something?
    I’m just curious. A fairly simple work-around would be to crop the topo map in an area of interest, an just use that instead.
    Thanks for sharing!

    1. You are correct Paul. The topo map has a smaller extent than the larger satellite imagery. If both images were originally the same size then you would need to crop one to get the same result as shown above.
      However, another way to display maps of the same size draped on topography would be to increase the transparency of one map. This would allow the other map to show through. In this case you might have the satellite map as the lowest layer, and then overlay this with a semi-transparent topography map.

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