Horizontal Accuracy Standards for Geospatial Data

Some of the highlights of the new ASPRS Horizontal Accuracy Standards for Geospatial Data are the following:

1. Unlimited horizontal accuracy classes:
   The new standard was designed to fit any horizontal accuracy requirement no matter what technology, current or future, is used. Table 3 represents the new ASPRS horizontal accuracy classes.

   Table 3 The new ASPRS horizontal accuracy classes

   Horizontal Accuracy Class	RMSEx and RMSEy (cm)	RMSEr (cm)	Horizontal Accuracy at 95% Confidence Level (cm)	Orthoimagery Mosaic Seamline Mismatch (cm)
   X-cm	$\le \text{X}$	$\le 1.41*\text{X}$	$\le 2.45*\text{X}$	$\le 2*\text{X}$

    RMSE_r = RMSE_x ² +RMSE_y ²                     RMSE_r =Radial RMSE=Circular RMSE=Two−dimensional RMSE of X & Y 
2. Aerial triangulation results should be twice as accurate as the generated products:
   1. Ortho and planimetric maps ONLY: $\begin{array}{l}\hfill \end{array}$RMSE_x (AT) or RMSE_y (AT) = ½ * RMSE_x(Map) or RMSE_y(Map) and RMSE_z(AT) = RMSE_x(Map) or RMSE_y(Map)  of orthoimagery
   2. For ortho, planimetric maps, and elevation maps: $$RMSE_x(AT) , RMSE_y(AT)  or RMSE_z(AT) = ½ * RMSE_x(Map) , RMSE_y(Map)  or RMSE_z(DEM)
3. Control points for aerial triangulation should be twice as accurate as aerial triangulation:
   1. For ortho and planimetric maps ONLY: $\begin{array}{l}\hfill \end{array}$RMSE_x (GCPs) or RMSE_y (GCPs) = 1/4 * RMSE_x( Map ) or RMSE_y( Map ) and RMSE_z = 1/2 * RMSE_x( Map ) or RMSE_y( Map )
   2. For ortho/planimetric maps and elevation maps: $$RMSE_{x ^(GCPS)} , RMSE_{y ^(GCPs)} or RMSE_{z ^(GCPs)} = 1/4 * RMSE_x( Map ), RMSEy( Map ) or RMSE_z( DEM )

Table 4 lists common horizontal accuracy classes for geospatial mapping products.