Topographic Mapping Techniques
Traverse and Topographic Mapping
South Louisiana Community College Campus
=P A R T 1=
-1- Plan of study
The links to the videos on this page are for a class taught at the South Louisiana Community College (SLCC), Dept of Civil, Surveying, and Mapping. The videos require about 2 months of study to be able to complete and master.
The plan of study show a student how to process surveying points collected in the field.
Part 1: The first set of 8 videos, processing two coordinate systems
The first set of videos show techniques that were taught in the class room setting. The videos are presented here as reference material.
The first set of points is a traverse connecting a series of rebar monuments placed on the campus of SLCC. These points were processed and given XY coordinates of South Louisiana North American Datum (NAD) 1983 coordinates. This coordinates system is more exact than latitude and longitude using a mercator projection system.
The second set of points are topographical points for a coulee (creek) that runs inside the campus. The coulee itself has cemented sides and bottom. The points are relative points, that is to say without referencing the NAD83 coordinates. The coordinates are simply given a coordinate the first point with an easting of 5,000 and and a north of 7,000. The remaining points are placed in reference to this first point. This procedure is a common one in which a survey crew collects points over a series of days.
The goals then is to import into AutoCAD the first set of traverse points with the absolute NAD83 points and then to import into the same AutoCAD drawing the second set of points with relative set of points. The second set of points are then moved and rotated to match the traverse absolute NAD 83 points.
Part 2:The second set of 8 videos, aerial photos to add topography
This second set of videos are taught online.
This set of videos show how to import a street layer and to import google aerial photos into drawing prepared in the first set of videos. The streets are used to scale the photo.
Folio7 is an AutoCAD plugin (app) developed by the instructor as a set of keyboard commands. Additional information on Folio 7 is available on this website here.
The Folio 7 command are used to draw a wide range of mechanical, architectural, and vicil drawings; but also include a special set of command used in survey plat preparation.
Points is an AutoCAD plugin (app) developed by Tom Haws, a professional engineer in Mesa, Arizona on his website, HawsEDC.com, with a large array of useful surveying data sets, tables, and software tools. Pointsin was modified by Mike LeBlanc to work in tandem with Folio7.
This is a demonstration of how to download files used in the sixteen videos.
-3.1- Here is a link to the download page.
-3.2-Screen shots of folders and files as listed on a Mac operating systems.
First set of Folders
Second Set of Folders
This is a demonstration how to import just the points used in the traverse that we studied in there first part of the course. These points are a traverse on campus with an absolute set of coordinates in Louisiana South, State Plane, North American Datum 1983 (NAD83).
This is a demonstration how to connect the points in a clockwise manner. After the points are connected with lines, the lines are connected into a polygon. The polygon is measured having 8.8791 acres.If you do not get this answer, then you made a mistake. Please redrawn the polygon and measure it again.
This is aa demonstration of how to import the points marking the location of the two bridges and the edge of the coulee. You will get also points used in the control network that was created from the traverse as mapped in Video 5.
This is a demonstration of how to create four layers (Bridge_1, Bridge_2, Coule_NS, Coulee_EW) and the connect the points with lines.
This is a demonstration how to create a block from the drawing in the previous video by inserting that drawing into the drawing of the original traverse with an absolute set of XY coordinates in NAD83. After being inserted, the drawing is moved and then rotated to align it with the absolute control network.
=P A R T 2=
This is a demonstration how to import streets with the absolute coordinate system into a drawing with the coordinate system. The insertion point needs to be 0,0,0.
This is a demonstration how to copy google maps and then import them inside AutoCAD. Once inside, then blocks are created of the original photo along with reference points and survey lines with know bearings.
The photos are selected based on a common set of landmarks both in the photo itself and in the drawing. For example, the photo has both a clearly defined bridge and a street intersection. A survey line connects the bridge centerline and the street intersection. The insertion point of the photo is the bridge when it is blocked.
This is an demonstration how to use the blocks with google photos with marked reference points and survey lines. The blocks are scaled and and then placed to a common landmark found both in the drawing and in the photo. After placing the block, the photo is then rotated to align survey line in both the photo block and the drawing.
This is a demonstration of adding one additional photo into drawing completed in Video 11. How that photo is inserted determine the amount of error found in the resulting topography drawn in the next video.
-12.1 A second photo is inserted into the drawing.
-12.2- The common landmarks selected are the intersection of two streets and the traverse connecting them. The second photo is measured, and then blocked.
-12.3- The blocked second photo is then scaled and then inserted at a common landmark. to match the scaling in the existing drawing using a scale facto determined by measure the distance between the two land marks in both photos.
-12.4- After scaling, the photo is then rotated, again by measuring the angular difference between the landmarks and the traverse connecting these two points.
-12.5- The bridge appears in both in the original survey, the first photo, and the second photo. The centerline of the bridge is measured between the surveyed location and its location in the second photo.
-13- Draw topological features (buildings, parking lots, trees, foot paths and sidewalks, etc.)
-14- Add title sheet; select drawing scale
-15- Add vicinity map and calculate scale
-16- Plot map to PDF from model space