Edit a grid file in Surfer

Grids can be edited in Surfer using the grid editor. The grid editor contains various methods for editing the grid Z values. Editing the grid Z values will change the appearance of any grid-based maps. For example, the grid editor can be used to edit contours on a contour map or change the surface in a 3D surface map.

To edit a grid file in Surfer:

1. Right click on your grid-based map layer in the Contents window and click Edit Grid. Any Post, Classed Post, and vector or raster Base layers will be displayed as context layers to assist with editing the grid. Alternatively, if you don't have a grid-based map created, click Grids | Edit | Grid Editor, then in the Open Grid dialog, choose your grid file and click Open.
2. Your grid is opened in a Grid Editor window.
   
   By default the following are displayed:

• Node Labels - The default size is 8 points, so you may not see the labels until you zoom into the map further.
  
  You can edit the font and label properties in the Properties window after selecting Node Labels in the Contents window.
• Node Symbols - Black + symbols represent nodes with z data values, and blue x symbols represent nodes that are assigned NoData values. You can change the opacity of these symbols in the Properties window after selecting Node Symbols in the Contents window.
• Contours - Default contours are displayed to give you a good indication of what needs to be edited, but you can edit the contour levels, the line properties, and the opacity of the lines in the Properties window after selecting Contours in the Contents window.
• Color Fill - Contours are filled to give a better visual understanding of the grid. You can edit the color gradient and the opacity in the Properties window after selecting Color Fill in the Contents window. Additionally, you can decide whether or not to interpolate colors. Interpolating colors blends the fill colors in between NoData nodes and nodes with z values, where not interpolating colors uses a sharp boundary to the colors between NoData nodes and nodes with z values.

Unchecking the box next to any of these in the Contents window will turn them off in the grid editor document window.

3. To edit the grid file, the following tools exist (Grid Editor | Tools in the ribbon bar):

• Select - Allows you to select a specific node so you can change the Z value in the box above the grid editor document window.
  

• Brush - Allows you to assign a specific z value to multiple nodes at the same time. Define the brush size (in number of grid cells) and the desired z value, then click in the center of the area you wish to change the z values for. The contours and labels update to reflect the new z values.
  
• Warp - Warp the grid interactively by dragging nodes. So if I wanted to shift the values so the grid node value of the 5730 highlighted in blue below is 5726, 
  
  I would click on the 5726 node and drag it over to the 5730 node.
  
• The Brush size option in the toolbar is the same as the brush size for the Brush option.
• The Density option controls the weighting of the tool effect radially from the center of the brush. A Density setting of 1 (the minimum possible value) has maximum "feathering" or blending between the center of the brush and values just outside the brush. A Density setting of 100 (the maximum possible value) applies the tool mode effect to all nodes within the brush equally.
• The Pressure option controls the speed at which tool effects are applied as the values change as the brush is dragged.
• Smooth - Smooths grid node values within the brush with a moving 3x3 average filter. Brushsize, Density, and Pressure are the same as they were for the Warp tool.
  
• Push Down - Decreases grid node values touched by the brush. Brushsize, Density, and Pressure are the same as they were for the Warp tool.
  
• Pull Up - Increases grid node values touched by the brush. Brushsize, Density, and Pressure are the same as they were for the Warp tool.
  
• Eraser - Assigns the NoData value to each grid node touched by the brush.
  
• Eyedropper - Records the z value of wherever you click in the Z box above the grid editor document window. This is helpful for use with the brush, or if you just need to get the exact z value where something special is happening with your contours.
  
• When you're done editing your grid, click File | Save to save the changes to the grid file.
• If you used the Edit Grid rather than the File | Open command to begin editing the grid file, you can click Grid Editor | Options | Update Layer to update the map with the updated grid file. 

Updated September 2023