In Maptek Vulcan, triangulations and grids are used interchangeably for many tools. They are both used to represent 3D surfaces but converting from one to the other is often a confusing task. Due to the number of menu options that do almost the same thing, it is hard to find the right tool to convert surfaces efficiently. I know that I forget which menu option to use almost every time. This post shows the steps to convert a triangulation to a grid using the menu option: Model > Triangle Surface > Grid Mesh.
To convert a surface triangulation to a grid select the tool Menu > Triangle Surface > Grid Mesh. Fill out the ‘Grid Parameters’ panel, keeping the following in mind.
- X Mesh Size and Y Mesh Size refer to how big the cells in the resulting grid are. Smaller cell size will give more resolution but eat up more memory. Unless your topo is truly gigantic start with the default size of 25.0 for each mesh.
- The 'Use Default Window' checkbox will use the default extents of the primary window as the grid extents. Leave this checkbox unchecked. I will show you a trick a little later in this post to set the grid lines at regular intervals (100.000 instead of 100.051 for example). The default window often has an origin that is not a whole number.
- Grid Model Name – give your grid a unique name. To this name will be added the project prefix and the extension .sfg (surface grid).
- Display X Mesh Lines and Display Y Mesh Lines. Make sure that these boxes are checked. If these boxes are left unchecked, your grid won’t display in the primary window after creation.
Once you click ‘OK’ in the Grid Parameters panel, Vulcan will prompt you to ‘Indicate model origin point.’ Make sure that you are in plan view at this point. I like to specify a point that is farther east and south than the triangulation I am converting (0,0 for example). To do this click on the ‘Key in point data…’ icon in the ‘Digitise’ toolbar at the bottom of your screen. It looks like this:
Type in your X and Y coordinates and then click the ‘Create Point’ button. Next, you will be prompted to ‘Indicate model extent.’ Click a point farther west and north than your triangulation. This second point is not as critical as the origin point. Grid lines will be counted from the origin point but the extents point is just signaling the end of the grid data.
That’s it. Your grid will now be saved in the working directory with all the rest of your files. You can find this grid in the Vulcan Explorer under the 'Grids' virtual folder.