United States

Department of

Agriculture

Forest Service

Southern

Research Station

General Technical

Report SRS–79

ALOG User’s Manual: A Guide to

Using the Spreadsheet-Based

Artificial Log Generator

Matthew F. Winn, Philip A. Araman,

and Randolph H. Wynne
Jennifer D. Knoepp, Research Soil Scientist, and

James M. Vose, Project Leader, U.S. Department of

Agriculture, Forest Service, Southern Research Station,

Coweeta Hydrologic Laboratory, 3160 Coweeta Lab Road,

Otto, NC 28763.

The Authors:

Matthew F. Winn and Philip A. Araman are Forestry Technician

and Project Leader, respectively, U.S. Department of Agriculture,

Forest Service, Southern Research Station, Blacksburg, VA 24060;

Randolph H. Wynne is Associate Professor of Forestry, Department

of Forestry, Virginia Polytechnic Institute and State University,

Blacksburg, VA 24060.

March 2005

Southern Research Station

P.O. Box 2680

Asheville, NC 28802

Disclaimer

The application tool described in this publication is available upon request with the understanding

that the U.S. Department of Agriculture cannot assure its accuracy, completeness, reliability, or

suitability for any other purposes than that reported. The recipient may not assert any proprietary

rights thereto nor represent it to anyone as other than a Government-produced computer tool.

The use of trade or firm names in this publication is for reader information and does not imply

endorsement by the U.S. Department of Agriculture of any product or service.


ALOG User’s Manual:

A Guide to Using the Spreadsheet-Based

Artificial Log Generator

Matthew F. Winn, Philip A. Araman, and Randolph H. Wynne



Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Hardware and Software Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

User Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Main Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Select Log Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Select Log Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Generate Log Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Grade the Generated Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Export Log and Defect Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Key to Defect Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Graded Log Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Appendix A: Troubleshooting Guide for Diagnosing

and Fixing Problems Encountered When Using ALOG . . . . . . . . . . . . . . . . . . . . . 9

Appendix B: Defect Codes, Associated Defect Types,

and Descriptions of Log Defects Generated in ALOG . . . . . . . . . . . . . . . . . . . . . . 11


Abstract Computer programs that simulate log sawing can be valuable training tools for sawyers, as well as a means

of testing different sawing patterns. Most available simulation programs rely on diagrammed-log

databases, which can be very costly and time consuming to develop. Artificial Log Generator (ALOG) is a

user-friendly Microsoft® Excel®-based program that accurately generates random, artificial-log data. The

program’s design is based on information from an analysis of real red oak (Quercus rubra L.) logs, which

ensures the validity of the data. Information about generated-log features includes length, small- and largeend inside-bark diameters, amount of sweep or crook, and defects. External defect attributes include type,

location, length, width, and height. Some internal defect information, including depth, volume, and angle,

is also given for the most common defect types. The user can either specify the log’s grade and its position

in the tree, or have the program randomly draw features from known distributions. Finally, the program

incorporates a grading algorithm to check the grade of the generated log. This user’s guide provides all the

information necessary to install and run ALOG, and to interpret program output.

Keywords: Artificial logs, defect generation, log defects, log generation, red oak, sawing simulation.

Introduction In today’s competitive markets, the forest products industry continues to look for

ways to improve mill productivity and profitability. Technological advances in

sawmill equipment have led to increased production efficiency and improved product

yield. However, most of the decisionmaking in log processing is still performed by

equipment operators. The processing decisions they make directly affect product

value. Training sawyers and other production workers is essential to a profitable

sawmill operation, but an alternative to on site training is becoming increasingly

attractive. Computer software can now simulate sawmill processes and provide the

necessary training to sawyers.

The Artificial Log Generator (ALOG) program provides realistic hardwood log data

in a spreadsheet format for log sawing simulation programs that require accurate and

detailed log feature information. One such program is the Log Computer Aided

Sawyer Trainer (LogCast), which was developed by researchers in the Department of

Industrial and Manufacturing Systems Engineering at the University of MissouriColumbia, in collaboration with the Southern Research Station of the U.S.

Department of Agriculture Forest Service (Forest Service) (Occeña and others 2000).

Such sawyer training programs usually draw log information from a database and

require modeling shape and defect information from an actual log. A more practical

method of getting log data is to generate both the log and defect attributes using a

computer program that considers real-log characteristics. Creating a computergenerated log is much faster, easier, and cheaper than physically modeling a real log.

Whereas a database, by definition, contains a finite number of logs, log descriptions,

or log types, a computer-generated log is always unique; just as every log a sawyer

encounters is unique.

Currently, the ALOG program uses only red oak (Quercus rubra L.) log data. Red

oak was chosen because of its wide distribution in the Eastern United States and its

use in a variety of products—from pallets to furniture. Information from the analysis

of external defect and log characteristics, and significant information on the

relationship between internal and external defect, were incorporated to ensure the

validity of generated logs.

ALOG can generate data based on log grade or position in the tree. Grades are Forest

Service standard grades for factory lumber logs (Rast and others 1973), and positions

include butt and upper logs. Program output consists of log size and shape attributes,

as well as external surface and internal defect attributes. However, internal defect
information in the current version of ALOG is given only for several defect and

attribute types. Future versions of ALOG will focus on expanding the internal defect

output to include more defect types and attributes.

By following this guide, the user will be able to install ALOG, generate red oak log

data based on desired input parameters, interpret program output, and export

generated log and defect data. The guide does not include detailed information about

methods used to generate data. For a more comprehensive explanation of the

program, see Winn and others (2004).

Getting Started

Hardware and Minimum system requirements include an IBM®-compatible PC with 30MB free

Software Requirements disk space and 128MB RAM. The program is not compatible with Macintosh®

operating systems. ALOG was developed using Microsoft® Excel® 2002 running

under Microsoft® Windows® 2000 and was not tested using other versions. ALOG

also requires the user to install two Excel® add-ins for the program to function

properly:

• Analysis ToolPak—financial, statistical, and engineering tools installed by default

with Excel®

• PopTools—matrix, stochastic process, simulation, and model fitting tools available for free from Commonwealth Scientific and Industrial Research Organisation

(CSIRO) Sustainable Ecosystems Web site (www.cse.csiro.au/poptools/)

User Requirements All user operations are point-and-click, so no prior Excel® experience is necessary to

use the ALOG program. In order to install and run the program, a general

understanding of how to navigate in the Windows environment is sufficient.

Installation Downloading from the Internet—ALOG can be downloaded at the following Web

site: www.srs4702.forprod.vt.edu. If Internet access is unavailable, contact Matthew

F. Winn, USDA Forest Service, Southern Research Station, Blacksburg, VA 24060

[(540) 231–8815].

Installing from a CD–ROM—Copy the file named ALOG.xls from the CD–ROM to

the computer’s hard drive.

Installing PopTools add-in—PopTools can be downloaded at the following Web

address: www.cse.csiro.au/poptools/. Follow the installation instructions on the

PopTools Web site.

Configuring Excel®—To function properly, Excel® must be reconfigured prior to

using ALOG. Use the File-Open option within Excel® to open the file named

ALOG.xls. Depending on your computer’s security settings, you may receive a

warning that the file contains macros. If so, click Enable Macros. The macros are

safe and must be enabled before using ALOG. Next, select Tools-Add-Ins. Confirm

that Analysis ToolPak and PopTools are checked. If the Analysis ToolPak is not

available, run Microsoft® Office® setup and install it. Click OK. Select Tools-Options

and click on the Calculation tab. Verify that the calculations are set to Manual. Click

OK. The program is now ready to use.
Overview ALOG is a Microsoft® Excel® workbook of 28 worksheets, 3 of which are user

viewable. The remaining 25 are used for calculations only and are hidden. When first

opened, the program displays the Main worksheet (fig. 1). Here the user specifies

input parameters and generates log data. When the program has completed the

necessary calculations, the Main worksheet displays log and defect data. The user

can then verify the grade of a generated log, if desired, and also export results.

The Main worksheet (fig. 1) displays a link to another worksheet—Key to Defect

Types (fig. 2)—which asks the user to choose an appropriate Defect code. The

display provides Defect types corresponding to the selected codes, as well as a

detailed description of each type.

To view the generated log and defects, click on View Log, see “G” (fig. 1). A third

worksheet, titled Graded Log (fig. 3), will appear, displaying a view of the generated

log’s surface (“unrolled”) along with the program-determined grading face.

Main Worksheet The Main worksheet (fig. 1) is displayed by default when ALOG is opened. From

here the user specifies input parameters, generates log and defect data, and grades

the generated log. This also links the user to the Key to Defect Types and Graded

Log worksheets.

Figure 1—ALOG’s Main worksheet. Note: White circles with letters are for explanation purposes only and

do not appear on the Main Worksheet.


Figure 3—ALOG’s Graded Log worksheet showing an unrolled view of a sample log, its defects, and the grading face.

Figure 2—ALOG’s Key to Defect Types worksheet containing Defect Codes, Defect Type, and Defect

Description.


Select Log Position To select the generated log position in the tree, click on one of the two options listed

in the drop-down menu, see “A” (fig. 1). Select either position (butt or upper) or,

instead, allow the program to randomly assign log position. Upper logs are any

above the butt log.

Select Log Grade Click one of three options on the Select Log Grade drop-down menu, see “B” (fig. 1).

Available log grades 1, 2, and 3—in order of decreasing quality—are based on Forest

Service standard grades for hardwood factory lumber logs (table 1) (Rast and others

1973). The drop-down menu also provides the option of having the program

randomly generate log grade.

Table 1—Forest Service standard grades for hardwood factory lumber logs

Log grades

Grading factors F1 F2 F3

Position in tree Butts Butts and Butts and

only uppers Butts and uppers uppers

Scaling diameter (inches) 13–15a 16–19 20+ 11+b 12+ 8+

Length without trim (feet) 10+ 10+ 8–9 10–11 12+ 8+

Required clearcuttingsc of each

three best facesd

Minimum length, (feet) 7 5 3 3 3 3 3 2

Maximum number 2 2 2 2 2 2 3 No limit

Minimum proportion of

log length required in

clearcutting 5/6 5/6 5/6 2/3 3/4 2/3 2/3 1⁄2

Maximum sweep and crook

allowance

For logs with < 1⁄4 of end in

sound defects (percent) 15% 30% 50%

For logs with > 1⁄4 of end in

sound defects (percent) 10% 20% 35%

Maximum scaling deduction

(percent) 40%e 50%f 50%

End defect [see Rast and others

(1973), page18]

a Ash and basswood butts can be 12 inches if they otherwise meet requirements for small F1s.

b Ten-inch logs of all species can be F2 if they otherwise meet requirements for small F1s.

c A clearcutting is a portion of a face, extending the width of the face, that is free of defects.

d A face is 1⁄4 of the surface of the log as divided lengthwise.

e Otherwise F1 logs with 41 to 60 percent deductions can be F2.

f Otherwise F2 logs with 51 to 60 percent deductions can be F3.

Source: Rast and others (1973).


Generate Log Data After specifying input parameters, the user can generate log and defect data by

clicking on Generate Log, see “C” (fig. 1). The program will scroll through various

worksheets while performing calculations and should take only a few seconds to

produce results. Log and defect attributes for the generated log will then be

displayed on the Main worksheet.

Log attributes—Generated log attributes include log position, grade, length, smalland large-end inside-bark diameters, sweep, crook length, crook depth, and radial

orientation of sweep or crook, see “D” (fig. 1). Log grade and position will be the

same as the user specified unless the random option was selected. Log length is

given in feet and includes a random trim allowance. Both small- and large-end

diameters are given in inches and represent the average diameters measured through

the center of the cross section of the log, terminating at the cambium. Sweep is

measured in inches as the maximum deviation from straightness along the length of

the log. Similar to sweep, crook is defined as an abrupt deviation from straightness

along the length of the log. Crook length is given in feet, measured from the small

end of the log and includes the length of log affected. Crook depth is the maximum

deviation in inches from the straight portion of the log. Finally, the radial location of

sweep or crook (S/C Deg.) is the angular orientation of the defect relative to an

arbitrary 0° reference point on the log ends.

Defect attributes—External defect attributes included in ALOG output consist of

defect type, surface location, length, width, and height, see “E” (fig. 1). Note that

the program supports only surface defects, not end defects. An explanation of each

defect type code can be found in the Key to Defect Types worksheet. A hyperlink to

the defect key is available in the lower right section of the Main worksheet, see “F”

(fig. 1).

ALOG uses two parameters to locate an external defect: location length and location

degree. Location length is the distance from the large end of the log to the center of

the defect. Location degree is the angular orientation around the log from an

arbitrary reference point to the center of the defect. The program uses three

parameters to describe the size and shape of the external defect: length, width, and

height. All are measured in inches. Defect length is measured along the length of the

log and defect width is measured perpendicular to defect length. Defect height is the

maximum perpendicular distance from the defect to the normal (defect free) log

surface.

Internal defect information is also available for several defect types and attributes.

Internal defect attributes include depth, volume, and angle. Depth is the maximum

distance in inches that the defect extends below the cambium perpendicular to the

log surface. Defect volume is the total space occupied by the defect inside the log

and is measured in cubic inches. Angle is the orientation of the defect relative to the

pith and is measured in degrees.

Due to the numerous random variables used in generating external defect

parameters, occasional defect overlapping will occur. When this happens, the

violating defects will be highlighted yellow in the Defect Attributes section. Where

defect types overlap, the user can regenerate the log in order to avoid unrealistic

external defect placement.


Grade the Generated Log Using random variables in log and defect generation may result in a mismatch of

the actual grade of the generated log with the grade specified in the input. After

generating a log, click Verify Grade, see “G” (fig. 1) to determine the actual grade.

A number representing the generated log’s actual grade will appear in the Actual

Grade box, see “H” (fig. 1). If the log does not meet the minimum requirements for

a grade 3 log, it will be denoted as below grade (BG). If the actual grade matches

the grade specified, the box will be highlighted green; if not, it will be red, see “I”

(fig. 1). In either case, the log generated is still a reasonable sample; it just has a grade

different than that specified. If the specified and actual grades differ, the user can

update the grade in the Log Attributes table by clicking on Grade, see “B” (fig. 1).

Before exporting log data from the program, the user should enter or verify the log

grade.

When log grading is complete, click on View Log, see “J” (fig. 1) to view a rudimentary representation of the generated log and its defects. Additional information is

presented under the Graded Log worksheet section.

Export Log and Defect Data Exporting to Excel®—Click on Select Log Data, see “K” (fig. 1), then on Copy

Data to Clipboard, see “M” (fig. 1). Open the Excel® worksheet where you want to

store the data. Select the area where you want to place the data and select Paste

under Edit in the main menu. Repeat this process to export defect data by clicking

on Select Defect Data button, see “L” (fig. 1).

Exporting to a text file—Often it is useful to export data in a format that is easily

readable by other programs. To export the data to a tab-delimited or fixed-width text

file, click on the appropriate button (for log or defect data). Select the Export Range

to File option under the PopTools menu. Follow on-screen directions to save the

selection to a text file.

Key to Defect Types From the Main worksheet, click on Defect Key, see “F” (fig. 1) to access the Key to

Defect Types worksheet (fig. 2). This worksheet contains the defect codes, the type

of defect, and a brief description of each type. A listing of all defects generated by

ALOG is also shown in appendix B. To view a specific defect type, select a defect

code from the pulldown menu in the upper left section of the worksheet and click Go.

Click Return to Top below each defect description to return to the top of the worksheet. To return to the Main worksheet, click on the link in the upper right corner of

the page (fig. 2). Defect descriptions are taken from Bulgrin (circa 1960), Carpenter

and others (1989), and Rast (1982).

Graded Log Worksheet A simple, unrolled view of the generated log is available on the Graded Log worksheet (fig. 3), which is accessible by clicking on View Log on the Main worksheet,

see “J” (fig. 1). The image displays the log length, in feet, along the x-axis and the

distance around the circumference of the log on the y-axis, expressed in degrees

from an arbitrary reference point. Surface defects are represented by red rectangles

and are based on the defect length and width generated by the program. If a defect

overlaps the arbitrary circumferential reference mark (0°), a portion of the defect

will be displayed on the top of the unrolled log; the remaining will be displayed on

the bottom. Defects that are not considered grading defects (light bark distortions,


open sound seams, open bird peck, sound wounds, and flanges) will not be used in

determining log grade and are not shown on the log image.

The grading face chosen by the program is displayed on the log and represents the

second-worst face, according to the Forest Service standard log grading rules. Note

that there may be more than one equivalent grading face, but the program only

displays the first one when moving from the top to the bottom of the screen. For a

more detailed explanation of the Forest Service log grading rules, see Rast and

others (1973). Other information available on the Graded Log worksheet includes the

log length, small- and large-end diameters, log position in the tree, the grade

specified by the user, and the actual grade of the log. To return to the Main

worksheet from the Graded Log worksheet, click Return to Main Page (lower right

area of the screen).

Literature Cited Bulgrin, E. [Circa 1960]. Manual of standard procedures for diagramming hardwood trees and primary

products. Intern. Doc. [Place of publication unknown]: U.S. Department of Agriculture, Forest Service.

41 p.

Carpenter, R.D.; Sonderman, D.L.; Rast, E.D.; Jones, M.J. 1989. Defects in hardwood timber. Agric.

Handb. 678. Washington, DC: U.S. Department of Agriculture. 88 p.

Occeña, L.G.; Santitrakul, E.; Schmoldt, D.L. 2000. Hardwood sawyer trainer. In: Meyer, D.A., ed.

West Virginia now—the future for the hardwood industry: Proceedings of the 28th annual hardwood

symposium. Davis, WV: National Hardwood Lumber Association: 43-47.

Rast, E.D. 1982. Photographic guide of selected external defect indicators and associated internal defects

in northern red oak. Res. Pap. NE–511. Broomall, PA: U.S. Department of Agriculture, Forest Service,

Northeastern Forest Experiment Station. 20 p.

Rast, E.D.; Sonderman, D.L.; Gammon, G.L. 1973. A guide to hardwood log grading. 2d ed., rev. Gen.

Tech. Rep. NE–1. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station. 31 p.

Winn, M.F.; Wynne, R.H.; Araman, P.A. 2004. ALOG: a spreadsheet-based program for generating

artificial logs. Forest Products Journal. 54(1): 62-66.
	

Appendix A

Troubleshooting Guide for Diagnosing and Fixing Problems

Encountered When Using ALOG

Problem Solution

Defect data section on the Main worksheet is Select the Add-Ins option under Tools in the main menu.

always empty after generating logs or cells in Verify that the checkboxes next to the Analysis ToolPak and

the log and defect data sections are filled with PopTools are selected. If the Analysis ToolPak is not avail-

“#VALUE!”. able, run the Microsoft® Office® setup again and install it. If

the PopTools add-in is not available, download it from the

Internet at www.cse.csiro.au/poptools/ and follow the

installation instructions on the Web site.

The program takes an excessive amount of Select Options under Tools in the main menu and click on the

time to generate and grade logs or the pro- Calculation tab. Verify that the calculations are set to Manual.

gram stops responding.

When the Generate Log button is clicked, Restart the ALOG program. If a window appears warning that

a window appears stating that macros are the file contains macros, click the Enable Macros button. 

disabled.

Not all defects that are listed in the defect The following defects are not considered grading defects by

attributes section are shown on the log image. the program: light bark distortions, open sound seams, open

bird peck, sound wounds, and flanges. Therefore, they are

generated by the program but not used in calculating log

grade. They also do not show up on the log image.



Appendix B

Defect Codes, Associated Defect Types,

and Descriptions of Log Defects Generated in ALOG

Defect

code Defect type Defect descriptiona

AC Adventitious bud cluster A localized group of adventitious buds, often originating from

wounding or bruising of the cambium. Adventitious bud clusters often

develop into clusters of short-lived fine twigs; when this happens, a

bump usually develops that contains small bark pockets along with the

twig knots.

AD Ant or bark scarrer If a hole has remained open for a period of time, decay fungi can enter.

damage Carpenter ants will then excavate the rotten wood and enlarge the

galleries to make their nest cavities. Recent fresh attacks by the bark

scarrer appear as open holes about one-quarter inch or less in diameter.

They are identified by their round, irregular outline and by their

nonpenetration of the wood. The work of the bark scarrer and borers

results in a frothy exudation, which turns a dirty brown. Bark scarrer

attacks can result in an overgrowth, appearing as a vertical slit with

callus area on both sides.

AK Individual adventitious Subnormal buds found at points along the stem. They arise from latent

bud or dormant buds in the leaf axils of the young stem and persist for an

indefinite number of years within the cortical-cambial zone. These buds

can be activated at any time during the life of the tree in response to

various stimuli, leading to the development of an epicormic branch.

B Bump A protuberance on the tree or log surface that is overgrown with bark. It

may be abrupt with steep surfaces, or it may be a smooth undulation

that tapers gradually in all directions to the normal contour of the log.

The majority of bumps cover projecting sound or rotten limb stubs, a

cluster of adventitious buds, or a concentration of ingrown bark over a

scar.

BS Butt scar Generally a triangular-shaped break in the bark or wood at the butt end

of the first log caused by fire, logging, or other means.

Bu Bulge A general enlargement of the stem of a tree or log—a barreling effect—

often without an evident cause such as a knot or callus formation. It

may be near a branch stub, rotten knot, knothole, wound, or other point

of entry for fungi that can cause rot. It usually suggests a cull section,

the extent of the rot indicated by the farthest limits of the deformation.

CBPk Closed bird peck Occluded holes caused by bird attacks that are filled with callus tissue.

Holes can appear singularly, linearly, or in groups. Damage usually

extends into the wood in the form of bark flecks, callus pockets, and

stain spots.

(continued)


Appendix B

Defect Codes, Associated Defect Types,

and Descriptions of Log Defects Generated in ALOG

Defect

code Defect type Defect descriptiona

CL Closed lesion A relatively localized, spindle-shaped necrotic canker consisting

primarily of bark and cambium. A lesion starts as a small area of dead

bark resulting from a wound caused by cambium-mining insects,

mechanical wounding, fungal diseases, or gnawing of the bark by red

squirrels. A spot of gum then appears, and gum continues to ooze

through the bark down the trunk, where it hardens and darkens.

DK Dead knot Remnant of a branch consisting of all or a part of the stub. The knot

consists of dead tissue but shows no presence of decay and may be as

hard as the surrounding wood. 

DKC Dead knot without Remnant of a branch consisting of all or a part of the stub. The knot

callous growth consists of dead tissue but shows no presence of decay and is covered

or surrounded either partially or wholly with callous growth.

Fla Flange Triangular, buttress- or wing-like formations projecting from the base

of the butt log. Exaggerated projections of the normal stump flare

sometimes extend 7 or 8 feet and seem to be related to wetness and

softness of site. Flanges occur outside the milling frustrum of the log

but have no relation to blemishes in the underlying wood. Flanges are

not considered grading defects in factory lumber logs.

GBS Overgrown bark seam A seam that has healed to the point where a patch of bark is partially or

wholly enclosed in the wood.

GD Grub damage A scar in the bark resulting from grub work. Usually a sharp pucker

consisting of a pitted core, not over 1/4 inch in diameter, surrounded by

callous tissue and distorted bark over an area 3/4 inch to 2 inches in

diameter. In severe cases a round “plaster” of callous tissue as large as

3 inches in diameter may occur.

GSS Overgrown sound seam Longitudinal radial separation of the fibers in a log overgrown with

callous tissue and showing no signs of decay. They are usually caused

by wind, frost, or lightening.

GSU Overgrown unsound seam Longitudinal radial separation of the fibers in a log overgrown with

callous tissue but has decay beneath and possibly to the sides of the

callous. They are usually caused by wind, frost, or lightening.

HD Heavy bark distortion An indicator of an overgrown knot identified by the characteristic

pattern of concentric circles encompassing the defect indicator. Bark

distortions differ from “overgrown knots” in that there is no height

associated with the indicator. 

(continued)


Appendix B

Defect Codes, Associated Defect Types,

and Descriptions of Log Defects Generated in ALOG

Defect

code Defect type Defect descriptiona

KCl Knot cluster Two or more knots or branches growing in a more or less inseparable

group and usually elevated above the normal surface.

LD Light bark distortion An indicator of an overgrown knot identified by the characteristic

pattern of concentric circles encompassing the defect indicator. Light

distortions show only a slight amount of curvature in the surrounding

bark plates, and the bark pattern shows only slight variance from

normal. Since the internal knots associated with light bark distortions

are usually buried deep within the log, it is not considered a grading

defect in factory-grade logs. Bark distortions differ from “overgrown

knots” in that there is no height associated with the indicator. 

MD Medium bark distortion An indicator of an overgrown knot identified by the characteristic

pattern of concentric circles encompassing the defect indicator.

Medium distortions show signs of the concentric circles, but the circles

are broken in several areas by the normal bark pattern starting to

reform. Bark distortions differ from “overgrown knots” in that there is

no height associated with the indicator. 

MH Medium hole Unoccluded openings in the bark, 3/16 to 1/2 inch in diameter, which

sometimes penetrate into the wood beneath. They include entrance and

emergence holes of wood-boring insects, increment-borer and tap holes,

and openings made by sapsuckers. 

OBPk Open bird peck Unoccluded openings in the bark caused by bird attacks. Generally, the

holes show no signs of callus tissue formation. Open bird peck is an

indication of a recent attack and usually doesn’t affect the underlying

wood. Open bird peck is not considered a grading defect in factory

lumber logs.

OK Overgrown knot A knot that has been completely overgrown but is clearly outlined by

circular or other configurations in the bark. Overgrown knots differ

from bark distortions in that there is an obvious height attribute of the

defect when compared to the normal log surface. 

OKC Overgrown knot without A knot that has been completely overgrown but is clearly outlined by

callous growth circular or other configurations in the bark. The knot is covered or

surrounded either partially or wholly with callous growth.

OKCl Overgrown knot cluster Two or more overgrown knots growing in a more or less inseparable

group.

(continued)


Appendix B

Defect Codes, Associated Defect Types,

and Descriptions of Log Defects Generated in ALOG

Defect

code Defect type Defect descriptiona

Op Operational defect Cracks, splits, brooming, splinter pull, “barber chair,” holes, etc., that

result from felling, skidding, or loading.

Oss Open sound seam Longitudinal radial separation of the fibers in a log with no evidence of

callous tissue or decay. They are usually caused by wind, frost, or

lightening. Open sound seams are not considered a grading defect in

factory lumber logs.

R Rot Advanced decay, not identifiable with a knot or branch.

RK Rotten knot A knot where advanced decay is present and extends beyond the area of

the limb stub.

RKC Rotten knot without A rotten knot covered or surrounded either partially or wholly with

callous growth callous growth. Advanced decay is present and extends beyond the area

of the limb stub.

SK Sound knot Remnant of a branch consisting of all or a part of the stub. The knot

shows no indication of decay and is as hard as the surrounding wood.

SKC Sound knot without Sound knot covered or surrounded either partially or wholly with

callous growth callous growth. The knot shows no indication of decay and is as hard as

the surrounding wood.

SW Sound wound Damage to the stem due to natural causes such as a limb falling against

another tree or from logging. The wood underneath is sound and

callous overgrowth may be open or closed or any degree of coverage of

the wound. Sound wounds are not considered a grading defect in

factory lumber logs.

UK Unsound knot Remnant of a branch consisting of all or a part of the stub. The knot

shows presence of decay and is not as hard as the surrounding wood.

The amount of decay is normally confined to the limb stub.

UKC Unsound knot without Unsound knot covered or surrounded either partially or wholly with

callous growth callous growth. The knot shows presence of decay and is not as hard as

the surrounding wood. The amount of decay is normally confined to the

limb stub.

a Defect descriptions taken from Carpenter and others (1989), Rast, (1982), Bulgrin (circa 1960).

Winn, Matthew F.; Araman, Philip A.; Wynne, Randolph H. 2005. ALOG user’s manual: A guide to using the

spreadsheet-based Artificial Log Generator. Gen. Tech. Rep. SRS-79. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Research Station. 13 p.

Computer programs that simulate log sawing can be valuable training tools for sawyers, as well as a means of

testing different sawing patterns. Most available simulation programs rely on diagrammed-log databases, which can

be very costly and time consuming to develop. Artificial Log Generator (ALOG) is a user-friendly Microsoft®

Excel®-based program that accurately generates random, artificial-log data. The program’s design is based on

information from an analysis of real red oak (Quercus rubra L.) logs, which ensures the validity of the data.

Information about generated-log features includes length, small- and large-end inside-bark diameters, amount of

sweep or crook, and defects. External defect attributes include type, location, length, width, and height. Some

internal defect information, including depth, volume, and angle, is also given for the most common defect types.

The user can either specify the log’s grade and its position in the tree, or have the program randomly draw

features from known distributions. Finally, the program incorporates a grading algorithm to check the grade of

the generated log. This user’s guide provides all the information necessary to install and run ALOG, and to

interpret program output.

Keywords: Artificial logs, defect generation, log defects, log generation, red oak, sawing simulation.
The Forest Service, United States Department of

Agriculture (USDA), is dedicated to the principle of

multiple use management of the Nation’s forest

resources for sustained yields of wood, water, forage, wildlife, and

recreation. Through forestry research, cooperation with the States

and private forest owners, and management of the National Forests

and National Grasslands, it strives—as directed by Congress—to

provide increasingly greater service to a growing Nation.

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activities on the basis of race, color, national origin, sex, religion,

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Persons with disabilities who require alternative means for

communication of program information (Braille, large print,

audiotape, etc.) should contact USDA's TARGET Center at (202)

720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director,

Office of Civil Rights, Room 326-W, Whitten Building,

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