How to use HRSCview

HRSCview is a web interface to the Mars Express HRSC image archive at the Freie Universitaet Berlin. It carries out on-the-fly image subsetting, stretching, compositing, and the the case of perspective views, projection of map-projected data-products. Access to the images is provided through a footprint map, by coordinates or by image identifier. The site is provided jointly by the Freie Universitaet and the German Aerospace Center (DLR).

Map view

The map view is defined by the latitude and longitude of the centre of the displayed image, the map scale in metres/pixel, and the view size: the dimensions of the display window in the form, width x height. Each of these can be modified directly - press 'Update View' to see the effect of a change.

Base map

The underlying base map can be switched on or off using the adjacent checkbox. It's possible to select from four base maps: MOLA shaded relief, MOLA colourised elevation, HRSC/SRC resolution - where the colour scale indicates resolution, and HRSC/SRC coverage, which uses varying shading of the colourised MOLA base map. Note that because of the high resolution and low coverage of the SRC images, their coverage will only be visible when coverage or resolution maps are shown at a map scale of around 2000m/pix or less.

IAU place names (courtesy USGS Astrogeology Science Center) may be displayed by selecting the checkbox.

HRSC layer

Also switched on or off using the adjacent checkbox. Several modes are offered for viewing HRSC images. Each may be pan-sharpened using the Nadir channel by selecting the appropriate checkbox. For the three colour modes (Mars-like, raw and enhanced), the red channel may be substituted by the IR channel by selecting the checkbox.

- nadir: the highest resolution, downward-looking channel of HRSC

- height: a colour-scale stereo-derived DTM

- slope: a slope map obtained from the stereo-derived DTM

- Mars-like: a predefined colour-stretch intended to give an approximation to the colours which might be observed at the surface

- raw: each colour channel presented as captured by the camera

- enhanced: each colour channel stretched independently and then squared, to enhance colour differences

SRC layer

May be switched on or off using the checkbox. Note that HRSCview displays only one SRC mosaic at a time: zoom in on the image of interest for it to be displayed.

Navigation controls

There are several ways to select a region of interest:

- click in the displayed image: the view will be recentred, and the coordinates of the point you clicked will appear in the latitude/longitude boxes. Clicking beyond the edge of an image will take you into an adjacent image if there is one

- enter the desired surface coordinates into the latitude/longitude boxes: the view will be recentred on the chosen point

- if you know which image you are interested in, enter its number directly into the Identifier box. The view will centre on the image. At surface points covered by more than one image, the image identifier box will contain a list of the images to select from

- click one of the four direction arrows beneath the image to pan left, right, up or down

Zoom controls

Aside from entering a map scale directly into the box, you may use the zoom in/out buttons to double or halve the displayed resolution.

Update view

After making changes to the image settings, press the Update view button to generate a fresh view.

Scale bars

The grey scale bar indicates the distance scale in the current view. The colour bar, when present, indicates the range of altitudes in the present scene, or the surface slope in degrees.

Download image product

When there is a valid image identifier in the box, a download link appears, which brings up the science data-product page. From there it is possible to download full image strips.