Showing posts with label 3D anaglyph. Show all posts
Showing posts with label 3D anaglyph. Show all posts

Wednesday, 30 November 2016

The Souness Martian glacier-like forms - looking at the lowest and highest elevation objects

Colin Souness, in his 2012 paper listed a total of 1309 'glacier-like forms' on the surface of Mars, in the mid-latitudes centred around 40° latitude, found from Mars Reconnaisance Orbiter context camera images.

In my dissertation (version for tablets) I studied descriptive statistics of them, including the distribution by elevation.

Since then, I have produced a web index to the objects, including a Top Trumps page for each object. I below show a table of links to the 30 Souness objects at the lowest and highest elevations. The Mars Express High Resolution Stereo Camera digital terrain model tile is shown where there is coverage, and it is also indicated where there are HiRISE images, or 3d anaglyphs that intersect with the outline of the object. These are linked to from the Top Trump page.

The elevation distribution looks as follows:
Elevation histograms for Souness object extents and head areas, compared with the overall elevation distribution in the coverage of the HRSC DTM tiles used

Slope histograms for Souness object extents and head areas, compared with the overall slope distribution in the coverage of the HRSC DTM tiles used
Showing the ratio of the GLF distribution as a function of elevation and slope / elevation and slope distribution in the HRSC tiles for extents.
The GLF distribution as a function of elevation  / elevation distribution in the HRSC tiles for the head areas.

The GLF distribution as a function of slope  / slope distribution in the HRSC tiles for the head areas.
I noted in the dissertation that that the numbers of glaciers appeared to be depleted below elevations of -3000m relative to Mars datum. There are two types of explanation for this, firstly that they were not formed, or secondly that they were more rapidly ablated. Fewer may have formed in the range -5000 to -3000 due to slope effects, with a large proportion of the these elevations being made up of the flat plains in the northern hemisphere, and the Martian glaciers are preferentially found on slopes. Alternatively in the higher-obliquity epoch, ablation may have been favoured at low elevations, due to higher temperatures, and possibly wind-stripping of debris cover allowing sublimation.


The outliers at the extreme ends of the elevation distribution may be of interest, since they may show something about what limited the distribution of Souness objects on Mars.

There is a secondary peak in the distribution at very low elevations. These could have formed at a later epoch at a lower obliquity in a cooler climate where glacier accumulation was only significant at the lowest elevations.
It is also an interesting question whether the objects at very high elevations formed at the same epoch as the main distribution, or whether these come from an older, more extreme obliquity epoch.




Lowest and highest 30 Souness glacier-like forms

Based on mean elevation of 5km circular radius buffer (from Souness et al. 2012 paper)

Lowest elevation 30 GLFs (buffer mean from Souness catalog):

Catalog numberElevation (m)RegionHRSC DTM tileCentre LatitudeCentre LongitudeArea (sq. km)N HiRISE footprints intersectingN anaglyphs intersecting
1130-6664West of HellasH2613_0000-32.5156.615.6300
1123-6603East of Hellasnone-35.6275.610.8000
1126-6540West of Hellasnone-30.8264.500.7100
1119-6534East of HellasH2195_0000-44.2983.562.8500
1122-6533East of Hellasnone-35.5675.580.7900
1120-6466East of HellasH2195_0000-44.3083.572.9200
1118-6001East of HellasH2631_0001-42.7185.991.3500
1301-5507East of HellasH2631_0001-39.8286.160.7500
1302-5456East of HellasH2631_0001-39.8286.140.8410
193-5431Utopia Planitia and Phlegra Montesnone38.59137.201.0310
1117-5334East of HellasH2631_0001-39.8286.160.7000
1114-5283East of HellasH2609_0000-38.2288.122.2400
1300-5227East of HellasH2631_0001-39.8286.1718.4700
198-5137Utopia Planitia and Phlegra MontesH1526_000038.93116.361.9931
200-5108Utopia Planitia and Phlegra MontesH1526_000039.08116.073.6210
1112-5097East of HellasH0365_0000-40.9790.172.0510
1113-5077East of HellasH0365_0000-40.9990.160.6110
194-5025Utopia Planitia and Phlegra MontesH2878_000040.12120.161.9610
199-5019Utopia Planitia and Phlegra MontesH1526_000039.05116.050.5910
195-5008Utopia Planitia and Phlegra MontesH2878_000040.11120.232.6410
1115-4981East of HellasH2609_0000-38.2188.064.7400
196-4958Utopia Planitia and Phlegra MontesH2878_000040.58120.398.7800
1111-4886East of HellasH0365_0000-40.6290.283.0700
197-4881Utopia Planitia and Phlegra MontesH2878_000040.52120.536.1100
1116-4860East of HellasH2609_0000-38.6287.948.0100
1131-4842West of Hellasnone-35.2051.268.6400
1103-4588East of HellasH0528_0000-38.5494.372.0021
1134-4193West of Hellasnone-35.6148.982.1400
1110-4187East of HellasH0550_0000-36.5190.170.8400
3-4161Deuteronilus MensaeH3253_000038.33-9.762.4100

Highest elevation 30 GLFs (buffer mean from Souness catalog):

Catalog numberElevation (m)RegionHRSC DTM tileCentre LatitudeCentre LongitudeArea (sq. km)N HiRISE footprints intersectingN anaglyphs intersecting
8447681TharsisH0453_0000-40.65-92.249.0110
8456928TharsisH0266_0000-40.91-94.500.9300
8466784TharsisH0266_0000-40.93-94.520.8800
8486708TharsisH0266_0000-40.95-94.581.4400
8476662TharsisH0266_0000-40.95-94.561.6000
825894Olympus Mons and surrounding areanone41.69-110.671.1600
8505407TharsisH0508_0000-40.90-97.601.0000
8495301TharsisH0508_0000-40.81-97.940.8100
8515101TharsisH0508_0000-40.92-97.491.0200
8524556TharsisH0508_0000-41.85-97.551.2210
8534445TharsisH0508_0000-41.86-97.491.1310
814139Olympus Mons and surrounding areaH5405_000044.92-111.193.2900
8274101TharsisH4087_0000-35.01-79.641.0100
793927Olympus Mons and surrounding areanone38.33-103.580.6710
8233799TharsisH2596_0001-35.48-75.244.9700
8183769Tharsisnone-36.62-70.774.2010
8543762Tharsisnone-42.32-98.610.8400
8663675TharsisH4234_0000-42.08-124.737.1000
8173626Tharsisnone-36.60-70.544.6010
10343533East of HellasH2356_0002-40.83103.0220.4921
7943475Argyrenone-50.59-58.6110.5600
12873444East of HellasH2279_0001-42.76108.159.7100
8253441TharsisH2607_0000-41.95-76.951.4700
8193433Tharsisnone-36.61-70.471.5710
7643404ArgyreH2669_0000-38.90-48.013.9010
8593210TharsisH2644_0000-49.59-113.368.6000
8243196TharsisH2640_0000-41.49-77.0213.8710
8623188TharsisH0424_0000-43.42-121.984.3100
10433155East of HellasH0451_0000-37.89103.3817.2921
9983134East of HellasH1887_0000-42.03109.5938.6200

Based on mean HRSC DTM elevation of immediate head area (100m radius)

Lowest elevation 30 GLFs (head):

Note that a terminus elevation of 0 is due to the terminus falling in a no data area.
Catalog numberHead elevation (m)Termimus elevation (m)RegionHRSC DTM tileHead LatitudeHead LongitudeArea (sq. km)N HiRISE footprints intersectingN anaglyphs intersecting
1130-6858-7173West of HellasH2613_0000-32.5056.655.6300
1119-6667-6943East of HellasH2195_0000-44.2783.582.8500
1120-6639-6918East of HellasH2195_0000-44.3083.602.9200
1118-5779-6047East of HellasH2631_0001-42.7085.991.3500
1117-5550-5647East of HellasH2631_0001-39.8386.170.7000
1301-5550-5663East of HellasH2631_0001-39.8386.160.7500
1302-5430-5659East of HellasH2631_0001-39.8486.130.8410
198-5251-5718Utopia Planitia and Phlegra MontesH1526_000038.90116.381.9931
1300-5180-5595East of HellasH2631_0001-39.2186.1818.4700
1113-50500East of HellasH0365_0000-40.9990.170.6110
200-4996-5782Utopia Planitia and Phlegra MontesH1526_000039.08116.043.6210
1115-4937-5051East of HellasH2609_0000-38.1988.074.7400
1112-49340East of HellasH0365_0000-40.9790.192.0510
199-4927-5397Utopia Planitia and Phlegra MontesH1526_000039.05116.040.5910
1114-4912-5228East of HellasH2609_0000-38.2288.102.2400
1116-4861-5262East of HellasH2609_0000-38.6587.988.0100
1111-4775-5282East of HellasH0365_0000-40.6190.253.0700
1103-4691-5009East of HellasH0528_0000-38.5594.342.0021
1-4222-4534Deuteronilus MensaeH5314_000037.89-5.9310.9531
2-4149-4530Deuteronilus MensaeH5314_000037.99-5.9618.9531
1110-4037-4049East of HellasH0550_0000-36.5090.180.8400
6-3805-4014Deuteronilus MensaeH1498_000030.59-11.342.7910
192-3772-4407Utopia Planitia and Phlegra MontesH1317_000034.24144.324.3920
3-3746-4196Deuteronilus MensaeH3253_000038.32-9.782.4100
120-3691-3845Olympus Mons and surrounding areaH1258_000134.22-177.334.7100
121-3684-4010Olympus Mons and surrounding areaH1258_000134.22-177.336.5800
4-3677-3914Deuteronilus MensaeH3253_000038.27-9.311.3500
5-3604-4058Deuteronilus MensaeH3253_000040.04-10.362.5000
299-3447-3681Nilosyrtis MensaeH1629_000042.4762.491.4000
1299-3393-4112East of HellasH0550_0000-35.3091.181.6571

Highest elevation 30 GLFs (head):

Catalog numberHead elevation (m)Termimus elevation (m)RegionHRSC DTM tileHead LatitudeHead LongitudeArea (sq. km)N HiRISE footprints intersectingN anaglyphs intersecting
84474847166TharsisH0453_0000-40.63-92.209.0110
84870786647TharsisH0266_0000-40.94-94.591.4400
84769806616TharsisH0266_0000-40.94-94.571.6000
84569716730TharsisH0266_0000-40.90-94.510.9300
84669596679TharsisH0266_0000-40.92-94.530.8800
84956245096TharsisH0508_0000-40.80-97.930.8100
85054394826TharsisH0508_0000-40.88-97.601.0000
85151904766TharsisH0508_0000-40.91-97.491.0200
85248224204TharsisH0508_0000-41.83-97.551.2210
85345664025TharsisH0508_0000-41.84-97.501.1310
82741833695TharsisH4087_0000-35.00-79.641.0100
8139143587Olympus Mons and surrounding areaH5405_000044.91-111.213.2900
86637973217TharsisH4234_0000-42.05-124.717.1000
82337293628TharsisH2596_0001-35.44-75.274.9700
128736341951East of HellasH2279_0001-42.82108.199.7100
76436272737ArgyreH2669_0000-38.89-48.063.9010
82535292918TharsisH2607_0000-41.93-76.971.4700
10433367752East of HellasH0451_0000-37.81103.3917.2921
86233172847TharsisH0424_0000-43.40-121.994.3100
85932491968TharsisH2644_0000-49.55-113.338.6000
10343225-175East of HellasH2356_0002-40.70103.0120.4921
86331002827TharsisH0424_0000-43.42-122.024.3600
82630422691TharsisH2607_0000-41.92-76.892.5700
129030131087East of HellasH2356_0002-41.71104.1221.9810
82229392606TharsisH2596_0001-37.19-72.320.9200
82429262282TharsisH2640_0000-41.48-77.1213.8710
86128922332TharsisH2197_0001-51.24-113.672.0400
104228251510East of HellasH0451_0000-37.83103.324.6321
10152800569East of HellasH2345_0000-44.83104.7515.2620
76327802162ArgyreH2669_0000-38.54-48.031.1200

Sunday, 2 October 2016

Souness Martian Glacier Top Trumps

I have made some additions and improvements to my website that lists the glacier like forms on Mars detailed by Colin Souness, and presents Mars Express data and links to HiRISE coverage from the Mars Reconnaisance Orbiter.

See an example here:
taklowkernewek.neocities.org/mars/sounesstoptrumps_js.html?S1003

The data is processed using some obsfucated Python code, which uses a combination of RSGISlib, GDAL via the command line and ImageMagick to provide a subset of the HRSC data to a bounding box of the 'context' shapefile of each Souness glacier (relying on the manual identification of the 'best' HRSC footprint with DTM coverage in the dissertation work).

This presents the panchoromatic nadir image, digital terrain model, a layerstack combining HRSC image and DTM, overlaying the classifier as calculated for glacier head areas in my dissertation, or else falling back to the Mars Global Surveyor coverage in which case a lower resolution image and DTM only are available.

Overlap with HiRISE, and HiRISE anaglyphs/DTM with the extents and wider 'context9' shapefiles were automatically identified, and also the level 3 HRSC images (the ND3 links).

If you open two browser windows, you and a friend can actually play the game of Top Trumps by the first player drawing a 'card' with the choose random button, choosing a category to play, and then the second player presses their random button and see if they beat them.

It is up to you if you want to play with north good, or high elevation good etc.

The page showing one of the Souness glacier-like forms in the southern hemisphere on Mars.

Showing the High Resolution Stereo Camera aboard Mars Express digital terrain model.

Indicating HiRISE coverage with a yellow overlay, which shows that there isn't coverage over the footprint of this object, but there is in the general vicinity. See below for an example of another Souness object where there is both HiRISE and anaglyph coverage.

A layerstack consisting of the panchromatic nadir image from HRSC (mapped to red), the slope of the DTM (green), and the elevation (blue). These are locally scaled within the bounding box of the 'context' shapefile, which is the white box visible (the extent) scaled up by a factor of three.

The data table. Links are given to Mars Express data from the Nasa Mars Orbital Data Explorer, Arizona State University, and Freie Universität Berlin, MRO context camera also from Arizona State University and HiRISE data from University of Arizona.
Elevation profile using the h2279 HRSC terrain model.

Slope profile using the h2279 HRSC terrain model.
Object number 716 in the Souness catalog has overlay with HiRISE and HiRISE anaglyph footprints, which are distinguished by being written in bold in the table.

Saturday, 14 November 2015

Utopia Planitia

Most of the North of Mars is covered by a low, flat plain.

As such, there are few Souness GLFs, these being found in the walls of craters.

Here is the area of part of Utopia Planitia, north of the shield volcanoes Elysium Mons and Hecates Tholus.

I had originally titled this 'Elysium Planitia' which is in fact in another location south of the Elysium Mons massif. The URL will continue to reflect that.

Overview

Screenshot from Google Earth showing colourised hillshaded MOLA elevation

 

A small number of Souness GLFs are found inside craters in Utopia Planitia.

Elevation colour ramp used for HRSC tiles in this area.

Hillshaded MOLA elevation.

MOLA elevation colour ramp.

 Four HiRISE anaglyphs overlap or are in the vicinity of Souness GLFs:

Zooming into the area covered by HRSC tiles h1526 and h2878.

Zooming in further to several areas of interest:

Crater at 116°E, 39°N containing 3 Souness GLFs, with HiRISE anaglyph coverage of one of them. HRSC tile h1526 nadir image with the classifier results.

3D anaglyph PSP_007884_2195
A crater further north in tile h1526 at 43°N without any catalogued Souness GLFs, though there looks to be remnants of some kind of flow features.

Classifier results show topography favoured for glaciers.
Google Earth screenshot with HiRISE CTX imagery of crater containing Souness 193 which is not covered by any HRSC DTM tiles. The HiRISE anaglyph referenced earlier covers a portion of the eastern wall.
Kufra Crater at 120°E, 40°N. (HRSC tile h2878 nadir image)

Bayesian classifier results (note DTM is only at 250m resolution).
Google Earth screenshot of HiRISE CTX imagery of Kufra crater.


Friday, 13 November 2015

Nilosyrtis Mensae

Continuing the exploration of the northern hemisphere elevation dichotomy boundary eastward, the Nilosyrtis Mensae area is also rich in Souness glacier-like forms:

HRSC DTMs blended with nadir image.


This is the elevation colour ramp used for all HRSC DTMs in this region.

MOLA elevation.

MOLA elevation blended with hillshade.


Auqukuh Vallis (word for 'Mars' in Quechua)

The Auqukuh Vallis system shows some striking examples of GLFs, and is highly favoured by the Bayesian classifier:

HRSC DTM (tile h1446 at 61°E, 31°N) blended with nadir image. Two Souness GLFs are found within this area, including HiRISE anaglyph coverage of the terminus of S312 (PSP_003482_2115).

The nadir image alone.

Nadir image with classifier for head (red) and extent (blue) areas overplotted.


Another part of the Auqukuh Vallis system at 62°E, 32°N:

Five Souness GLFs are shown in this region, with HRSC DTMs of h1446 and h5173 overlaid on nadir images.

Nadir image alone

With classifier overplotted.
A curious feature at 62.5°E, 32.5°N.

Eastern Nilosyrtis

Around 68°-75°E,  28°-34°N:
HRSC DTM tiles (h1391, h5378, h5360, h5342, h5324, h5306) blended with nadir image.
Nadir images only.

Nadir images with classifier overplotted.
The HiRISE anaglyphs ESP_013160_2135, ESP_020597_2135 and ESP_014307_2130 are in the vicinity of, but do not overlap Souness GLFs. 

Closeup of part of tile h5342:
Many Souness GLFs are to be found in this area around 73°E, 30°N.


The classifier picks out areas of the south side of the mesa which do not have Souness GLFs catalogued. Is it possible that glaciers in south facing areas at this relatively low latitude for Souness GLFs were ablated more readily?
Closeup of part of tile h5306 around 75°E, 30°N:

Again the 2 Souness catalogued GLFs are found on the northern side of the mesa only.



HiRISE 3D anaglyph ESP_027823_2100 showing S204.


Close up of h5234/h5306, showing an area further south at 28-29°N:
The southern valleys below 28°N have no Souness catalogued GLFs. The set around 74°E, 28.5°N are the southernmost Souness GLFs in the entire northern hemisphere, except S201 at 77.15°E, 27.78°N at two others in crater Lockyer at 160°E. 27.5°N. 
Nadir images only
Nadir images with classifier.

A closer view. The size of the alcoves suggests that the GLFs here may be the remnants of larger objects that have ablated.