Working with Grids | Back to User Tips

There are 3 major ways to work with Grids in a scene. Depending upon what you need, one may be better or easier than another.

Overviews:

1)  Snap/Grid

Snap/Grid covers the drawing area with an invisible grid. With Snap/Grid activated, the cursor can only select objects which are positioned directly on the grid. The crosshairs will not deviate from the Snap/Grid and will bounce from one to the next, jumping across the space between the Snap/Grid.

2) Show/Draw Grid Surface command

This is a powerful 3D command allowing you to draw a Grid over a job based upon a Surface. The Grid is in full 3D and can be drawn as lines or dots. The Grid is not labeled.

3) Array command

This command allows you to start with a simple point and create a Grid of points by specifying the number of rows and columns along with the spacing for each. The new points will be copies of the original so if it was 2D then the others are 2D. If it was 3D then all of the new points have the same elevation. If this command is used in conjunction with a Surface then we can Drape the points onto the Surface and have them take on the elevation of the surface at that point.

Details:

1.       Snap/Grid

Snap/Grid can be setup from two different locations.

A) MapScenes and MapScenes Pro, go to the Settings menu -> then pick on Settings -> then select the Snap/Grid tab on the dialog box.

There are four sections to the Snap/Grid dialog:

Snap Grid: This option allows you to set the spacing by which your crosshairs will jump from one place to another. Setting a Snap Grid to 1 would mean the crosshairs would jump every one unit and not be able to go part way between them. The Origin and Snap Angle can also be set. The status bar shows the x,y,z movement and when you are in a command, the status bar shows the length being drawn

Grid Spacing: This option currently does not work. It was meant to allow the temporary grid points to be placed on an even spacing over the drawing. Future versions will have this available. When this option is made available again, you will also have two additional commands to control how much area the Grid will cover. LIMMIN will define the lower left corner of the area and LIMMAX will define the upper right corner of the area. Both of these commands can be typed at the command prompt.

Isometric Snap Grid: Not used very often but can be handy when creating an isometric view of a scene.

Orthogonal Mode: Forces the crosshairs to draw and edit lines either perfectly vertical or horizontal in movement.

B) You may also access the same dialog by picking on the button below the S (shown below). These buttons can be found near the top left of your program screen.

The O button turns the Orthogonal Mode on and off. The S button turns the Snap Grid on and off (using the values set in the dialog box). The G button normally makes the grid spacing visible on screen (using the values set in the dialog box), but at present time does nothing. Future versions will have this available.

2) Show/Draw Grid Surface command

The Show/Draw Grid Surface command has Many options that can affect how the Grid appears on screen. Before we look at a few of these options we need to remind you that to use this Show/Draw Grid Surface command you first need to create a surface under the Surface menu. To create a surface (I am going to show you a simple way that may not always be the correct way for your data), go to the Surfaces menu -> Extract From Drawing -> Extract to Surface. This will ask you for the surface name to use, and defaults to GROUND. Simply pick on OK and then select all the points in your drawing. If you have Breaklines to extract then follow the same procedure as we did for points, using the same surface name.

Now we have a Surface ready to create a Grid. Lets look at the defaults available to control the Grid. Under the Surfaces menu -> Configuration Settings -> Grids.

The 2 important sections of this dialogue for drawing a Grid are, Cell Size and Grid Registration. This allows us to control the spacing between the grid lines and where the grid lines start so they can match your survey datum.

If Cell Size is set as Auto, then you do not know what the Grid spacing will be. The program will give you an arbitrary spacing that will normally not be what you need. Turn the Auto off and specify the X and Y spacing manually. I used 20 in this example.

Grid Registration when not enabled, will see the Grid start in the lower left corner and fit the grid in as best it can but the grid will not match and specific survey points. If you Enable the Grid Registration then you can specify a base point that the grid will be forced to go through. The example above shows it using a point of 0,0. This allows you to control which survey point to reference the grid to.

The rest of the dialogue box can be ignored by most of our customers as the options are very specific to the type of work you are doing and most do not require the options. If you find you do need them then please refer to the on-line help for more details on the options.

Now that the options are set as desired, we can run the Show/Draw Grid Surface command under the Surfaces menu. This will use the settings we chose and allow us to generate a Grid for the drawing. In this case we wish to Draw a grid and we will use DOTS. (you may also choose to draw the Polyface, Mesh or 3D Faces as grids. These will be 3D solid formations instead of simple dots) Each Dot will have the correct elevation based upon the surface used, so each point is in full 3D automatically.

Surface name <GROUND>:
None/Show/Draw/Redraw <Show>?Draw
Dots/3dFaces/Polyface/Mesh <Polyface>:Dots

You may also see notes such as the following. If you do then you may have some discrepancies with any data found around the breaklines.

Note: The current surface contains breaks which the grid will cross
Use a Triangulated Grid to honor the break lines

Now that the 3D dots have been drawn on screen we can either use them as is, or add them to our Database. From either the TOGGLES command or the HOT TOGS button, there is a setting to control the Next Point Number. Be sure to set this to start at the range you wish to use to add the points. Now go to the MapScenes pulldown menu -> Coordinate Point Utilities -> Auto Add Points to Objects. This command allows you to select lines, curves and Points and add them to our Database. Be sure to only pick the Dots we just created above. They will be added to the database starting at the point you set above.

Now you can use the points as desired.

3) Array Command

The Array command can be used for many different items and can be done as a multiple copy type command by using Individual as the option, or rotated arrays can be done using the CircNRot or CiRot options - but we are concerned with the Rectangle option in this example. To start with we must draw a point on the screen to use as the base point. I would draw this at the reference location for this job. To do this run the POINT command and type in or pick the exact location desired for the point. Now run the Array command (found under the Modify pulldown menu) and choose the Rectangle option. Select the Point you just drew and press enter. Now tell us how many Columns and Rows to generate (15 and 12 in this example) and the spacing between each (20 in this example).

Array
Individual> Rectang
Select objects:
1 selected.
Select objects:
*** 1 selected. ***
_RECTANG
No. of columns: 15
No. of rows: 12
Distance between columns: 20
Distance between rows: 20

This will create a Grid of 2D points. If you need to rotate the points to match a baseline then be sure to use the Rotate command under the Modify menu before continuing. To convert the points from 2D to 3D you would first need to create a surface (as in option 2 above) and a Tin generated by running the Show/Draw Triangulated Surface command under the Surfaces menu. Then with the Drape Objects command, found under the Surfaces menu -> Cross Section/Profiles, you can pick all of the 2D points generated by the Array command and project them onto the surface thereby converting them to 3D points.

 I hope this helps explain a few different ways to generate Grids, depending upon what you have and what you need.

Glen W. Cameron, C.E.T.
Technical Support Manager