For the next step TASH is used, a special software for topographic surveys developed by the university.From the angles and distances measured with the total stations, TASH calculates the coordinates and elevations of all points.Then the breaklines (blue lines in this map) are added by connecting the points manually. (This is a little tricky, a TASH isn't developed for being easily used by inexperienced people like us.)Then TASH calculates a digital terrain model using a TIN (triangulated irregular network).In the next step TASH uses the TIN too interpolate the elevations in a regular grid with 1 m distance between the points, resulting in a second digital terrain model.Finally this second terrain model is used to calculate the contours (black and red in this map).Theoretically, the contours could be calculated directly from the TIN, but this way they look better. (At least that's what I was told.)This picture shows the contours calculated by TASH, ready to be exported to ArcGIS for creating the final map.The area is the same as on the plan I drew. You can see how earth walls and ditches influence the contours.The strange round structure the 240 m contour forms in the bottom left is the result of a single point, where for reasons unknown a totally wrong horizontal angle was recoded, resulting in a elevation 14 m too high in this point.When comparing the map with the ground we didn't notice it at first, as there really was a little hill or mound in this position. However, in the 3D terrain model it was visible as a 12 m high "pyramid" so we noticed and deleted it.I had to resurvey this area a few days later.
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Survey Photos by Tag or CategoryEarth's Largest Survey Photos Collection
Since 2007, Land Surveyors around the world have shared their best Surveying Photos from the field. Inside this collection you can transport yourself to virtually any location on Earth and see how Land Surveyors work, types of equipment being used and environmental challenges associates with being a land surveyor in that location.
Location Based Chapter Hubs also have photos specific to the locations they represent. You can use our Surveyor Apps for quick sharing of your photos from the field.
Note: Members who have uploaded their photos of surveying to this collection can also move their photos to location based hubs. To see how, follow this tutorial.
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