In this article you will learn how to calculate the layout grid of your ArcMap files in a professional way, keeping the symmetry of the lines that represent the EAST / NORTH coordinates.
It used to happen to me that when generating the flat coordinate grids for the layout I would start guessing about the correct spacing of the XY axes, and I would spend a lot of time on that task trying to get a graphical output that looked a bit harmonious to the eye. However, I have seen cases where the person in charge of the geographic information system, simply assigns flat grids without paying attention to details and obtains results like the following, where there is no symmetry in the horizontal and/or vertical coordinates:
So that you do not spend a lot of time like me or get results as in the previous example, I will show you how you can calculate that spacing of the XY axes (EAST-NORTH) with the following formulas that I devised:
Formulas for calculating flat grid spacing in ArcMap / ArcGIS.
X Spacing (EAST) = (Data Frame Width in cm)*(Scale)/(Number of divisions desired) * 100
Y Spacing (NORTH) = (Data Frame Height in cm)*(Scale)/(Number of desired divisions)*100
As you can see you will need the scale to use, the number of divisions that can be assigned by you, and the height and width of the Data Frame; these last two data can be consulted in the following way:
How to query the dimensions of a dataframe in ArcMap / ArcGIS layout ?
0. Make sure that the scale is set to the desired number, for example 1000000 in the “Standard” toolbar and that the view is as you want it.
1. Right click on the Data Frame (a).
2. Click on the “Properties...” button of the displayed submenu (b).
3. Go to the “Size and Position” tab (c).
4. In the “Size” section you will find the width “Width” and height “Height” (d).
While you can do the calculation with the formulas that I present in the section “Formulas to calculate the spacing of flat grids in ArcMap / ArcGIS”, you can also download the following Excel workbook (Link)
With this spreadsheet you only have to copy the width and height in cells E5 and E6, indicate the number of divisions in cell E4 and the denominator of the scale in E3. The division of the XY axes will be in cells E9 and E10.
Whatever your choice is, once you have the calculations, follow the next steps:
How to define the grid spacing for a Data Frame in ArcMap / ArcGIS layout?
1. Right click on the Data Frame (a). Click on the “Properties...” button of the displayed submenu (b).
2. Go to the Grids tab (c). Select the flat grid, which if it does not have a custom name should be called “Measured Grid” (d) and press the “Properties...” button of this window (e).
3. In the “Reference System Properties” window go to the “Intervals” tab (f) and paste there the result of the calculation in the items “X Axis Interval” and “Y Axis Interval” (g).
4. Make sure that the option “Use origin from the current coordinate system” is checked (h).
Result:
This way of calculation gives you a lot of flexibility, if you do not vary the scale and size of the dataframe it will adjust even if you change the geographic extent (Ideal when using Data Driven Pages). However, for more accurate jobs I prefer the procedure described in my Excel GIS article “Flat Grid Calculation Option 2” which I recommend.
I also recommend you to visit my article for the calculation of grids with geographic coordinates “Excel GIS Geographic Grid Calculation”.
NOTES
- It often happens that the NORTH-EAST coordinates collide in the corners, to solve this I recommend you to place some graphic elements like a white box in each corner.
I hope you enjoyed this article, soon I will upload a video explaining the procedure that you can consult in this blog. Save my blog among your favorite links, I will be uploading many more tricks of this style, remember that you can send me your concerns on the contact page or leave your comment, I will be attentive to respond.
