272
April 2015
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
Letter From Alan Mikuni
continued from page
As is the case for the horizontal accuracy conversion, the new
standard provides the following examples to relate vertical
accuracy measured according to the new standard to its
equivalents in the legacy standards.
Example 3: Converting the Vertical Accuracy of an
Elevation Dataset from the New Standard to the
Legacy ASPRS Map Standard of 1990.
Given:
an elevation data set with a vertical accuracy of
RMSEz = 10 cm according to the new standard, compute
the equivalent contour interval according to the legacy
ASPRS map standard of 1990, for the given dataset.
Solution:
The legacy ASPRS map standard of 1990 states that:
“The limiting rms error in elevation is set by the standard
at one-third the indicated contour interval for well-
defined points only. Spot heights shall be shown on
the map within a limiting rms error of one-sixth of the
contour interval.”
Because both standards utilize the same RMSE measure
to express the vertical accuracy, then the accuracy of the
elevation dataset according to the legacy ASPRS map
standard of 1990 is also equal to the given RMSEz = 10 cm.
Using the legacy ASPRS map standard of 1990 accuracy
measure of RMSEz = 1/3 x contour interval (CI), the equivalent
contour interval is computed according to the legacy ASPRS
map standard of 1990 using the following formula:
CI = 3 × RMSEz = 3 x 10 cm = 30 cm with Class 1,
or CI = 15 cm with Class 2 accuracy
However, if the user is interested in evaluating the spot
height requirement according to the ASPRS 1990 standard,
then the results will differ from the one obtained above. The
accuracy for spot heights is required to be twice the accuracy
of the contours (one-sixth versus one-third for the contours)
or:
For a 30 cm CI, the required spot height accuracy, RMSEz
= 1/6 × 30 cm = 5 cm
Since our data is RMSEz = 10 cm, it would only support
Class 2 accuracy spot elevations for this contour interval.
(
to
be
continued
)
The contents of this column reflect the views of the author,
who is responsible for the facts and accuracy of the data pre-
sented herein. The contents do not necessarily reflect the offi-
cial views or policies of the American Society for Photogram-
metry and Remote Sensing and/or Woolpert, Inc.
“for the first time, the new standard
provides users with a measure to
estimate the horizontal accuracy of
data derived from LiDAR.”
provided by these two papers on this latest disruption in the
science and technology of ASPRS.
ASPRS, in recognition of the expanding role of UAS in
society and The Society, established a UAS Division. ASPRS
would appreciate your participation in this new activity. Visit
to learn more. In October 2014, ASPRS’
NorthernCalifornia Region hosted a symposiumand technical
demonstration devoted exclusively to the topic of mapping
using UAS. “UAS MAPPING 2014 RENO” was a gathering
of 530 mapping science practitioners, scientists, researchers,
manufacturers, software developers, and others interested in
mapping with UAS. By most measures, the symposium was a
success. I am pleased that, on September 29-30, 2015, ASPRS
will be hosting “UAS MAPPING 2015 RENO”. Becky Morton
(chair of last year’s symposium) and I will be co-chairing the
2
nd
symposium and technical demonstration. Please visit
uasreno.org for further information, and I hope to see you in
Reno in September!
Alan Mikuni PE CP
ASPRS Past President and Co-chair UAS MAPPING 2015
RENO
GeoBytes!
ASPRS GIS
D
ivision
— F
ree
O
nline
S
eminars
The ASPRS GIS Division,
in cooperation with CaGIS
and GLIS, is sponsoring
free online live seminars
throughout the year.
Attention those seeking ASPRS
Certification: ASPRS Online Seminars
are a great way to gain Professional
Development Hours!
/
GISD-Division/Online-
Seminars.html
