.ig
	file pmp_book
	by Larry E. Wagner
	for Soil Erosion Research Methods
	Chapter entitled:
		Methods for Investigating Basic Processes
		and Conditions Affecting Wind Erosion

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.ce 2 
\fB
DIGITIZATION OF SURFACE PROFILE PIN METER PHOTOS
USING IMAGE ANALYSIS TECHNIQUES
\fP
.DS 0
by
Larry E. Wagner
Agricultural Engineer
USDA-ARS Wind Erosion Research Unit
Kansas State University
Manhattan, KS, USA  66506
.DE
.P
The importance of soil surface roughness
with respect to wind erosion is well documented (References here),
especially when adequate surface residue cover is unavailable.
Parameters that reflect the degree of surface roughness
are usually computed from surface elevation measurements
(lIST A COUPLE OF SURFACE ROUGHNESS PARAMETERS AND REFERENCES
- ALLMARAS'S ROUGHNESS COEFFICIENT AND THE SHELTER ANGLE CONCEPT FOR EXAMPLE).
These elevation measurements can be obtained
through a variety of methods that
use image analysis techniques (Rice, et al., 1988),
contain microprocessors (Radke et al., 1981),
employ laser systems (Huang, et al., 1988 and Romkens, et al., 1988),
and use photographic methods (Welch, et al., 1984)
to obtain the actual surface elevation data.
.P
One of the simplest devices is a
transect, surface profile, pin meter (TSPPM).
A typical TSPPM consists of a row of equally spaced pins
that contact the soil surface
when a measurement is to be taken.
The relative pin elevations are then recorded
either manually, electronically, or photographically
(Figure 1).
.P
Manual recording of field pin elevation data
is time consuming and prone to human errors.
Electronically recording field elevation data
is usually faster than manual techniques and
less likely to introduce human-induced errors
during the actual recording operation.
This is an attractive solution
when considering the fact that the
elevation data can be stored in a computer
readable digital format in the field.
However, automated electronic measurement requires
a data acquisition system, sensors, and power source
be available at the measurement site.
This means the cost of aquisition, maintenance, and repair
must be considered when implementing this type of system,
especially when multiple field instruments are necessary.
Also, electronic measurement devices
may require special instruction and training
in the operation and maintenance of the units
that may not be possible or feasible.
.P
The third method,
photographic techniques,
can be as fast as electronic means
for recording field pin elevation data (Figure 2),
but are less costly and generally
do not require special handling
and maintenance considerations
by the field technician.
The disadvantage of photographic techniques
is that the data still must be digitized
into discrete relative elevation values.
This digitization step can be performed
either manually or through some automated or semi-automated process.
.P
Recently, a PC-based computer program has been developed
to automate the digization of transect, surface profile,
pin meter elevation data encoded on photographs\*F.
.FS
Available from USDA-ARS Wind Erosion Research Unit,
Room 105B, East Waters Hall, Kansas State University,
Manhattan, KS, USA  66506
.FE
The Pin Meter Program (PMP)
eliminates the tedious time-consuming process
used in manual digitization methods
and reduces the amount of operator judgement
required in less automated digitization processes.
The PMP is designed to simplify the digitization step
and provide more consistent results.
.P
The PMP uses a computer-based hand or page digitizing scanner
to scan the photograph of a transect, surface profile, pin meter field data.
This digitized image is then processed
using image analysis techniques to locate the pin edges
and therefore compute the pin elevation data.
The PMP can then produce the data in the desired format
and units as selected by the operator.
The data may then be displayed on the monitor,
printed, and/or stored on disk.
This elevation data may then be used to obtain
the surface roughness parameters of choice.
The PMP does, however, require 
a minimum set of computer hardware and peripherals.
Those requirements are:
.AL 1
.LI
An IBM\u\(rg\d PC/XT/AT or compatible microcomputer with
640 kilobytes of main memory.
.FS " "
IBM\u\(rg\d is a registered trademark of International Business Machines, Inc.
.FE
.LI
MS-DOS or PC-DOS version 2.1 or higher operating system.
.LI
Additional computer memory
supporting the Lotus/Intel/Microsoft (LIM 4.0)
Expanded Memory Standard (EMS).
Approximately 1.5 megabytes of EMS memory is necessary
for a 7.6cm by 12.7cm (3x5 inch) photo digitized at 300 dpi.
The actual amount of EMS memory required is dependent
upon the size of the cropped digitized image and the
scanner digitizing resolution used.
.LI
An EGA or VGA graphics adapter with corresponding color
monitor is required.
Only the 16 color 640x350 pixel (EGA) or 640x480 pixel (VGA)
graphics modes are supported.
.LI
A Microsoft\u\(rg\d compatible mouse with the corresponding driver
software installed.
.FS " "
Microsoft\u\(rg\d is a registered trademark of Microsoft Corporation.
.FE
.LI
Digitizing scanner.
The scanner software must be capable of producing single plane
(black and white) digitized images that can be stored in the
PC Paintbrush\u\(rg\d (.PCX) graphics file format.
A relatively inexpensive hand digitizing scanner\*F\u\(dg\d,
as compared to more expensive page scanners,
used during the development of PMP
has provided satisfactory results.
.FS " "
PC Paintbrush\u\(rg\d is a registered trademark of Zsoft Corporation.
.FE
.FS
The actual hand scanner used was a DFI Handy Scanner model HS-3000
by DFI ------ LOOK UP COMPANY NAME AND ADDRESS.
.FE
.FS "\u\(dg\d"
The use of trade names in this publication
does not imply endorsement of the products named.
.FE
.LI
A hard disk is not required but highly recommended for convenient
storage and retrieval of image and surface profile data files.
.LE
.SP 2
.ce
\fBREFERENCES\fP
.VL
.LI
Huang, C., I. White, E.G. Thwaite, and A. Bendeli.
1988.
A noncontact laser system for measuring soil surface topography.
Soil Sci. Soc. Am. J.  52:350-355.
.LI
Radke, J.K., M.A. Otterby, R.A. Young, and C.A. Onstad.
1981.
A microprocessor automated rillmeter.
Trans. ASAE.  24:401-404, 408.
.LI
Rice, C., B.N. Wilson, and M. Appleman.
1988.
Soil topography measurements using image processing techniques.
Computers and Electronics in Agric.  3:97-107.
.LI
Romkens, M.J.M., J.Y. Wang, and R.W. Darden.
1988.
A laser microreliefmeter.
Trans. ASAE.  31:408-413.
.LI
Welch, R., T.R. Jordan, and A.W. Thomas.
1984.
A photogrammatic technique for measuring soil erosion.
J. Soil Water Conserv.  39:191-194.
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.SK
.AL 1
.LI
I have a slide that should make a good photo copy for Figure 1.
.LI
I should be able to find a good pin meter data photo for Figure 2.
.LE