Murray Lab Global CTX Mosaic of Mars: Version 1.0 Production Date: February 27, 2023 For updated information and publications, please visit: http://murray-lab.caltech.edu/CTX/ ### Quad: E-032_N68 ### This directory contains all data for the global CTX mosaic within the E-032_N68 quad (1 of 3,960). The quad covers the longitude range -32.0°E to -28.0°E and the latitude range 68.0°N to 72.0°N. This document provides information about these data. --------------------------- ## MurrayLab_CTX_V01_E-032_N68_Mosaic.tif ## The quad image mosaic file. Data are stored as 8-bit unsigned integer values with pixel values of 0 assigned as NoData. The file is georeferenced on the surface of Mars with the IAU 49912 coordinate reference system, which contains the following parameters: Projection: Equidistant Cylindrical Center Longitude: 0° Latitude Type: Planetocentric Equatorial Radius: 3,396,190 m Polar Radius: 3,376,200 m Proj4 syntax: '+proj=eqc +lat_ts=0 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +a=3396190 +b=3376200 +units=m +no_defs' .prj file syntax: PROJCS["Mars_2015_Ocentric_Equirectangular_clon_0",GEOGCS["GCS_Mars_2015_Ocentric",DATUM["D_Mars_2015",SPHEROID["Mars_2015",3396190.0,169.894447223612]],PRIMEM["Reference Meridian",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Plate_Carree"],PARAMETER["false_easting",0.0],PARAMETER["false_northing",0.0],PARAMETER["central_meridian",0.0],UNIT["Meter",1.0]] The quad mosaic has been blended with its neighboring quads. They render seamlessly within a GIS if no contrast stretch is applied or the same contrast stretch is applied to all quads. --------------------------- ## MurrayLab_CTX_V01_E-032_N68_SeamMap.shp ## The quad seam map. This is a vectorized polygon shapefile that maps which original CTX data file is represented in the blended image mosaic data. Data within 0.25° of the quad boundary on all sides could be data from a neighboring quad that was included during the tile-blending process. The attribute field “MOS_QUAD” identifies the quad that contributed the original data. The seam map contains 55 attribute fields for each feature, 51 of which are directly inherited from the CTX instrument itself. Descriptions of each field can be found via the PDS (https://pds-imaging.jpl.nasa.gov/data/mro/mars_reconnaissance_orbiter/ctx/mrox_0001/index/index.lbl). The four additional attributes that apply to the mosaic are: MOS_QUAD: The original quad from which the pixels were derived. Each quad was blended with its neighboring quad, so data that was originally blended in an adjacent quad could be rendered within the outer 0.25° of this quad. MOS_IMG: The original CTX image ID plus a two-digit suffix to differentiate portions of segmented data. CTX data that contained transmission gaps (labeled “ERROR” in the “DATA_QUALITY_DESC” field) were split into multiple segments during the mosaicking process, necessitating distinct identifying names (i.e. P20_008697_2074_XN_27N125W_02). Data that did not have transmission gaps (labeled “OK” in the “DATA_QUALITY_DESEC” field) have “_00” as the suffix. SESE_LINK: Link to the Arizona State University School of Earth & Space Exploration (SESE) page for the original CTX data used in the mosaic. PDS_IMG: Link to the Planetary Data System (PDS) raw IMG file for the original CTX data used in the mosaic. The seam map is georeferenced using the same projection information as described above for the image mosaic (Equirectangular, centered at 0.0°E, 0.0°N). The directory also contains the accompanying files that are linked to the .shp shapefile. These include MurrayLab_CTX_V01_SeamMap_E-032_N68.dbf, MurrayLab_CTX_V01_SeamMap_E-032_N68.shx and MurrayLab_CTX_V01_SeamMap_E-032_N68.prj. --------------------------- ## MurrayLab_CTX_V01_E-032_N68_TiePoints.shp ## The quad co-registration tie point distribution map. This is a vectorized point shapefile that maps the co-registration points between two images that were used to construct the mosaic. The shapefile contains 9 attribute fields which contain the following information: QUAD: The mosaic quad within which the tie points were constructed. IMG1: The CTX image that was shifted to match IMG2. IMG2: The CTX image that was static and served as a target for IMG1. Mode: The method by which the registration was performed (either “Auto” for automatically determined or “Manual” for manual registration). Xloc_Deg: The location in decimal degrees of the center point on the x-axis between the target location of a feature (where the feature exists in IMG2) and the best-fit shifted location of a feature (where the feature exists in IMG1). This is the value used for the longitude of the point feature. Yloc_Deg: The location in decimal degrees of the center point on the y-axis between the target location of a feature (where the feature exists in IMG2) and the best-fit shifted location of a feature (where the feature exists in IMG1). This is the value used for the latitude of the point feature. Xresid_m: The distance in meters along the x-axis between the target location of a feature (where the feature exists in IMG2) and the best-fit shifted location of a feature (where the feature exists in IMG1). This is the east-west offset in registration between IMG1 and IMG2 at this location. Yresid_m: The distance in meters along the y-axis between the target location of a feature (where the feature exists in IMG2) and the best-fit shifted location of a feature (where the feature exists in IMG1). This is the north-south offset in registration between IMG1 and IMG2 at this location. Residual_m: The straight-line distance between the target location of a feature (where the feature exists in IMG2) and the best-fit shifted location of a feature (where the feature exists in IMG1). This is the closest estimate of the true offset of two images in the mosaic at the tie point location. Xloc_Deg and Yloc_Deg were calculated using the Mars2000 geographic coordinate system: Proj4 Syntax: '+proj=longlat +a=3396190 +b=3376200 +no_defs' .prj file syntax: GEOGCS["Mars 2000",DATUM["D_Mars_2000",SPHEROID["Mars_2000_IAU_IAG",3396190.0,169.89444722361179]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]] Xresid_m, Yresid_m and Residual_m were calculated using an Azimuthal Equidistant projection centered in the middle of the quad. Proj4 Syntax: '+proj=aeqd +lat_0=70.0 +lon_0=-30.0 +x_0=0 +y_0=0 +a=3396190 +b=3376200 +units=m +no_defs' .prj file syntax: PROJCS["Mars_Azimuthal_Equidistant",GEOGCS["GCS_Mars_2000",DATUM["D_Mars_2000",SPHEROID["Mars_2000_IAU_IAG",3396190.0,169.8944472236118]],PRIMEM["Reference_Meridian",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Azimuthal_Equidistant"],PARAMETER["false_easting",0.0],PARAMETER["false_northing",0.0],PARAMETER["central_meridian",-30.0],PARAMETER["latitude_of_origin",70.0],UNIT["Meter",1.0]] Notes about the registration process: 1. Two neighboring images in the rendered mosaic may not have been registered to each other. For instance, if image A was registered successfully to image B, and image B was registered successfully to image C, but data from image B did not end up being included in the final mosaic, there is no direct reported offset for image A and image C in the mosaic as they were never directly tied to each other. 2. The geographic location of the tie points was calculated from the image-to-image registration, before the whole quad itself was registered to its neighboring quads. So the recorded location is slightly offset, though not significantly, from the actual pixels that were matched. Thus these points should be used as a guide when analyzing the mosaic and not trusted at the pixel-level. Original pixel-to-pixel registration locations are available by request from the Murray Lab. 3. Registration points for a pair of images could fall well outside the boundaries of the quad. Entire CTX frames were used to increase the chances of an automatic co-registration, even if those regions occurred outside of the quad. 4. During the course of the mosaic's production, some image pairs were co-registered but their control networks were not saved. Thus, for those, the data are co-registered but the residuals cannot be reported. This is mostly within the *_N64 and *_N-68 quads. The directory also contains the accompanying files that are linked to the tie point shapefile. These include MurrayLab_CTX_V01_TiePoints_E-032_N68.dbf, MurrayLab_CTX_V01_TiePoints_E-032_N68.shx and MurrayLab_CTX_V01_TiePoints_E-032_N68.prj. --------------------------- ## MurrayLab_CTX_V01_E-032_N68_TiePoints.csv ## This is a comma-delimited table that contains the same information as MurrayLab_CTX_V01_TiePoints_E-032_N68.shp. This is to facilitate work conducted outside of a GIS. --------------------------- ## MurrayLab_CTX_V01_E-032_N68_DataSheet.pdf ## This is a one-page document that shows the mosaic itself (left) and a rendition of the mosaic with its seam map and tie points overlain (right). This is to show how the data should appear within GIS software. The mosaic is rendered with no contrast stretch. Sublimated imagery data in the background is from the surrounding quads in the global CTX mosaic. Each frame is rendered with an orthographic projection centered in the middle of the quad. Proj4 Syntax: '+proj=ortho +lat_0=70.0 +lon_0=-30.0 +x_0=0 +y_0=0 +a=3396190 +b=3376200 +units=m +no_defs' .prj file syntax: PROJCS["MarsOrtho",GEOGCS["GCS_Mars_2000",DATUM["D_Mars_2000",SPHEROID["Mars_2000_IAU_IAG",3396190.0,169.8944472236118]],PRIMEM["Reference_Meridian",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Orthographic"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Longitude_Of_Center",-30.0],PARAMETER["Latitude_Of_Center",70.0],UNIT["Meter",1.0]] --------------------------- The Context Camera (CTX) was built by Malin Space Science Systems (https://www.msss.com/). CTX is on board the Mars Reconnaissance Orbiter, which was built by the Jet Propulsion Laboratory for NASA. The Murray Lab is a data visualization and analysis facility within the Division of Geological and Planetary Sciences at the California Institute of Technology (http://murray-lab.caltech.edu/). The Global CTX Mosaic project was funded by the NASA Planetary Data Archiving, Restoration, and Tools (PDART) program.