5:15 PM - 6:45 PM
[MIS16-P01] Automatic drawing and report compiling algorithm of the geological stratigraphic column for outcrops
Keywords:stratigraphic column, automation, outcrop, Mars
Current observation procedures of outcrops and generation of geological stratigraphic columns are based on the experience and judgment of expertized people. Thus, some training is required to conduct geological surveys. However, there are cases where objectivity cannot be guaranteed even by expertized people, and there is a possibility that the limited time available in the field may not be sufficient to allow for sufficient work time. By incorporating methods such as automation and algorithmization, it would be possible to create an index for these matters and also to conduct geological surveys more efficiently.
In this study, we focused on stratigraphic columns. The stratigraphic column is a visual-representing method that compiles information such as layer thickness, grain size, and constituents, etc. If the drawing can be automated, it is possible to create a stratigraphic column with the same standards. In addition, stratigraphic columns can be created from drone or satellite images of outcrops that cannot be directly observed, such as outcrops in geographically inaccessible locations or outcrops that are not on Earth.
The outcrop stratigraphic column we have envisioned is one that is created based on outcrop observation. Creating a stratigraphic column requires the measurement of layer thickness, grain size, and compositional composition. In this study, we attempted to automate the "layer thickness measurement" and "stratigraphic column drawing".
In this study, two patterns of algorithms were created: A) Extracting layer thickness from orthophotographs of outcrops, and B) Extracting layer thickness from elevation data.
First, we explain the construction method for algorithm A. First, draw a boundary line on an outcrop photograph. Next, binarize with the color of the filled-in lines as white and the others as black. Then, specify the lines for drawing the stratigraphic column (hereafter, wish line) on the binarized image, and the brightness values on the line are read and stored in a CSV file. This data is used to calculate the layer thickness. After inputting the data into the Excel file, draw the rectangles. The completed algorithm was able to draw the stratigraphic column as expected.
Next, the algorithm for extracting layer thickness from the DEM data is explained. First, the image and elevation data of the desired outcrop are extracted in QGIS, and a line is drawn at the point determined to be the strata boundary. Next, a wish line is drawn to intersect the line. The points of intersection of the boundary line and the wish line are automatically plotted using an analysis tool. The elevations of the plotted intersection points are read using the Point Sampling Tool plug-in and output as a CSV file. The data in this file is used to determine the layer thickness. The process is the same as in A., an algorithm for drawing a stratigraphic column was created for this pattern.
Using these algorithms, field tests were conducted on actual outcrops. The algorithm was compared with the layer thickness measured at an actual outcrop, and its operation was confirmed at other outcrops. For the comparison, the ratio of the measured/algorithm layer thickness was obtained, and the results showed that the layer thickness could be extracted in the range of 97±15%. Experiments on outcrops with a large number of layers were also successful, and the algorithm was able to draw a stratigraphic column.
The use of this algorithm in actual outcrops, both on terrestrial and extraterrestrial outcrops, reduces the burden of outcrop description and allows a large number of stratigraphic columns to be drawn in a short period of time. Even if in situ observation is difficult, layer thicknesses can be automatically extracted using images and topographic data.
In the future, the algorithm is expected to be used in conjunction with technologies such as the automatic delineation of layer boundaries for automation in geological surveys.
In this study, we focused on stratigraphic columns. The stratigraphic column is a visual-representing method that compiles information such as layer thickness, grain size, and constituents, etc. If the drawing can be automated, it is possible to create a stratigraphic column with the same standards. In addition, stratigraphic columns can be created from drone or satellite images of outcrops that cannot be directly observed, such as outcrops in geographically inaccessible locations or outcrops that are not on Earth.
The outcrop stratigraphic column we have envisioned is one that is created based on outcrop observation. Creating a stratigraphic column requires the measurement of layer thickness, grain size, and compositional composition. In this study, we attempted to automate the "layer thickness measurement" and "stratigraphic column drawing".
In this study, two patterns of algorithms were created: A) Extracting layer thickness from orthophotographs of outcrops, and B) Extracting layer thickness from elevation data.
First, we explain the construction method for algorithm A. First, draw a boundary line on an outcrop photograph. Next, binarize with the color of the filled-in lines as white and the others as black. Then, specify the lines for drawing the stratigraphic column (hereafter, wish line) on the binarized image, and the brightness values on the line are read and stored in a CSV file. This data is used to calculate the layer thickness. After inputting the data into the Excel file, draw the rectangles. The completed algorithm was able to draw the stratigraphic column as expected.
Next, the algorithm for extracting layer thickness from the DEM data is explained. First, the image and elevation data of the desired outcrop are extracted in QGIS, and a line is drawn at the point determined to be the strata boundary. Next, a wish line is drawn to intersect the line. The points of intersection of the boundary line and the wish line are automatically plotted using an analysis tool. The elevations of the plotted intersection points are read using the Point Sampling Tool plug-in and output as a CSV file. The data in this file is used to determine the layer thickness. The process is the same as in A., an algorithm for drawing a stratigraphic column was created for this pattern.
Using these algorithms, field tests were conducted on actual outcrops. The algorithm was compared with the layer thickness measured at an actual outcrop, and its operation was confirmed at other outcrops. For the comparison, the ratio of the measured/algorithm layer thickness was obtained, and the results showed that the layer thickness could be extracted in the range of 97±15%. Experiments on outcrops with a large number of layers were also successful, and the algorithm was able to draw a stratigraphic column.
The use of this algorithm in actual outcrops, both on terrestrial and extraterrestrial outcrops, reduces the burden of outcrop description and allows a large number of stratigraphic columns to be drawn in a short period of time. Even if in situ observation is difficult, layer thicknesses can be automatically extracted using images and topographic data.
In the future, the algorithm is expected to be used in conjunction with technologies such as the automatic delineation of layer boundaries for automation in geological surveys.