OSAC 2023-N-0003, Standard for Diagramming Scenes

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OSAC 2023-N-0003

Standard for 

Diagramming Scenes

Crime Scene Investigation and Reconstruction Subcommittee

Scene Examination Scientific Area Committee

Organization of Scientific Area Committees (OSAC) for Forensic Science
OSAC 2023-N-0003, Standard for Diagramming Scenes

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Draft OSAC Proposed Standard

OSAC 2023-N-0003 Standard

for Diagramming Scenes

Prepared by 

Crime Scene Investigation and Reconstruction Subcommittee

Version: 1.0

January 2023

Disclaimer:

This OSAC Proposed Standard was written by the Organization of Scientific Area Committees 

(OSAC) for Forensic Science following a process that includes an open comment period. This 

Proposed Standard will be submitted to the standards developing organization and is subject to 

change. 

There may be references in an OSAC Proposed Standard to other publications under development 

by OSAC. The information in the Proposed Standard, and underlying concepts and methodologies, 

may be used by the forensic-science community before the completion of such companion 

publications.

Any identification of commercial equipment, instruments, or materials in the Proposed Standard 

is not a recommendation or endorsement by the U.S. Government and does not imply that the 

equipment, instruments, or materials are necessarily the best available for the purpose.
OSAC 2023-N-0003, Standard for Diagramming Scenes

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1 Foreword

2 This document delineates standards and recommendations for the diagramming of a scene and 

3 physical evidence during scene investigations. The approach outlined is recommended as good 

4 professional practice even though the facts and issues of each situation require specific 

5 considerations and may involve matters not expressly dealt with herein. Not every portion of this 

6 document may apply to every incident or investigation. It is up to the individual capturing the data 

7 to apply the appropriate recommended procedures in this guide to a particular incident or 

8 investigation. In addition, it is recognized that time, and resource limitations or existing policies 

9 may limit the degree to which the recommendations in this document will be applied in a given 

10 investigation. The responsibility of the individual preparing the diagram for evidence preservation

11 and the scope of that responsibility varies based on such factors as the jurisdiction, the status of 

12 the individual as a public official and private sector investigator, indication of criminal conduct, 

13 and applicable laws and regulations. This document should be utilized in conjunction with local 

14 regulations and any requirements set forth by entities examining document evidence to inform or 

15 augment policies relating to collecting and preserving physical evidence. 

16 This document has been drafted by the Crime Scene Investigation and Reconstruction 

17 Subcommittee of the Organization of Scientific Area Committees (OSAC) for Forensic Science 

18 through a consensus process.

19 This standard provides guidance on some safety issues but is not exhaustive. It is the responsibility 

20 of the appropriate agency to develop a full health and safety plan.

21 All hyperlinks and web addresses shown in this document are current as of the publication date of 

22 this standard.

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32 Keywords: diagram; sketch; map; measurement; baseline; triangulation
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33 Table of Contents

34 1. Scope ....................................................................................................................................... 5

35 2. Referenced Documents............................................................................................................ 3

36 3. Normative References ............................................................................................................. 5

37 4. Terms and Definitions ............................................................................................................. 5

38 5. Significance and Use ............................................................................................................... 6

39 6. Quality Assurance.................................................................................................................... 7

40 7. Considerations ......................................................................................................................... 7

41 8. Documentation and Custody ................................................................................................... 8

42 9. Measurement Methods ............................................................................................................ 8

43 10. Output/Deliverables........................................................................................................... 13

44 Annex A (Informative) References............................................................................................... 15

45
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46 1. Scope

47 1.1 The scope of this document includes guidelines for the diagramming of a scene and 

48 physical evidence.

49 1.2 This document covers scene measurement and diagramming methods, as well as the 

50 translation of scene work to output.

51 1.3 If compliance with this standard is claimed, justification for any deviation from this 

52 standard must be documented.

53 2. Normative References

54 Standard for Scene Documentation Procedures (DRAFT)

55 3. Terms and Definitions

56

57 3.1

58 Azimuth

59 a reference direction is measured as a clockwise angle from the north. (Boots, 2010)

60

61 3.2 

62 baseline

63 the method used to measure items of evidence when there are numerous objects in the scene. 

64 This is accomplished by laying a tape measure down so that it crosses the entire room or area 

65 to be measured. This first tape measure becomes the baseline for all other measurements in 

66 the scene. Measurements are then made perpendicular from this tape by laying another tape 

67 measure at a 90-degree angle to the first tape and measuring out to the evidence. (NFSTC, 

68 2013)

69

70 3.3 

71 polar coordinate

72 method appropriate for an outdoor scene in which only a single fixed or reference point is 

73 present. This method measures the distance and direction (angle) of an object from a known 

74 reference point. The angle can be measured with either a large protractor or an optical device 

75 such as a transit or a compass. The protractor technique with a 360-degree protractor is useful 

76 for underwater scenes. (NFSTC, 2013)

77

78 3.4 

79 triangulation

80 a measurement method that utilizes two fixed permanent objects within the scene. 

81 Measurements are taken from each fixed point to each piece of evidence. (NFSTC, 2013)
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82 3.5 

83 photogrammetry

84 the art, science, and technology of obtaining reliable information about physical objects and 

85 the environment through recording, measuring, and interpreting images and patterns of 

86 electromagnetic radiant energy and other phenomena. (ASPRS, 2014, 597)

87

88 3.6 

89 terrestrial LiDAR scanning

90 a method for surveying tasks that acquires complex geometric data where each point is 

91 determined by the position (X, Y, Z) and the intensity (i) of the returning signal, also known 

92 as terrestrial laser scanning (RTI International, 2016). This method differs from a total station 

93 in its ability to automatically capture a large number of points in a predefined window. 

94 (FTCoE, 2022)

95

96 3.7

97 total station

98 a surveying instrument that uses a theodolite with an electronic distance meter to read slope 

99 distances from the instrument to a particular point. (RTI International, 2016)

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101 Alternate Def: An electronic instrument that combines a theodolite and EDMI to collect

102 angles and distances from the instrument to various points. (Boots, 2010)

103

104 3.8

105 mobile mapping

106 the collection of highly precise point cloud data provided by laser scanning systems on 

107 moving platforms with an integrated navigation solution (Puente et al., 2013)

108

109 3.9

110 global navigation satellite system (GNSS)/global positioning system (GPS)

111 a general term describing any satellite constellation that provides positioning, navigation, and 

112 timing services on a global or regional basis. (GPS.GOV)

113 4. Significance and Use

114 4.1 This practice is intended to provide a graphic representation of the scene and evidence at 

115 hand and in such a fashion as to allow another individual to interpret the particulars of the 

116 incident.

117 4.2 This practice is suggested for documenting conditions and data of a scene and evidence 

118 that may change or be lost with further scene investigation.

119 4.3 The primary use of this practice is to preserve pertinent information for use by technical 

120 experts and other technical personnel who may be called upon to reconstruct the events 
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121 surrounding the incident.

122

123 5. Quality Assurance

124 5.1 Verification of Measuring Equipment

125 5.1.1 Prior to being put into service, new measuring equipment shall be verified against 

126 a traceable standard to requirements defined by the agency according to the purpose of 

127 the measurement. For example, newly purchased measuring devices can be compared 

128 directly (either in their entirety or in representative sections) against a known calibrated 

129 measurement standard (e.g., a traceable ruler or tape). 

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131 5.2 Calibration of Measurement Tools

132 5.2.1 Whenever measurements are reported or directly impact reported results, the 

133 associated measuring device(s) shall be calibrated. A vendor accredited to ISO/IEC 

134 17025 shall be used when available.

135 5.2.2 The agency will specify calibration specifications according to the purpose of the 

136 measurement. Sources for calibration specifications may come from standards or 

137 equipment manufacturer recommendations. 

138

139 5.3 Q.C. Checks of Measuring Equipment

140 5.3.1 All equipment that collects measurements should be verified on a defined 

141 schedule against a traceable standard and meet acceptability requirements. The agency 

142 defines the verification schedule and requirements according to the purpose of the 

143 measurement.

144

145 5.4 Uncertainty of Measurement

146

147 5.4.1 Uncertainty of measurement considerations may vary depending on the agency's 

148 needs and should be considered and estimated when appropriate. Methods of 

149 estimating uncertainty are outside the scope of this standard.

150 6. Considerations

151 6.1 The diagramming and mapping described in this practice may be prepared by any 

152 person(s) in a formal capacity. Persons investigating in a formal capacity include but may 

153 not be limited to international, federal, state, and local officials, employers, owners, 

154 insurance personnel, and other technical experts.

155 6.2 When multiple methods are available, the method that maximizes the accuracy and 

156 reduces error should be chosen. Considerations for method selection should be 
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157 documented (i.e., Environmental factors, equipment availability, personnel availability, 

158 investigative circumstances).

159 7. Documentation and Custody

160 7.1 The minimum requirements for documentation can be found in Standard for Scene 

161 Documentation Procedures. 

162 7.2 All output/deliverables and supporting data shall be preserved according to agency 

163 evidence handling requirements.

164

165 8. Measurement Methods

166 8.1 General Considerations

167 8.1.1 Agency policy shall define the level to which measurements must be recorded 

168 (e.g., to the nearest 1⁄4") to include the process of rounding. 

169 8.1.2 The handling procedures for measuring devices can significantly affect the 

170 resulting value (e.g., sag in measuring tape, not perpendicular, etc.). Measurement 

171 methods shall specify the manner in which measuring devices are used to ensure 

172 measurements meet agency requirements.

173

174 8.2 Manual Methods

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176 8.2.1 Manual distance measurements are measurements recorded by hand using tape 

177 measures, roll-a-wheels, laser handheld distance measuring devices, etc.

178 8.2.2 Manual angle measurements indicate the degree of angles and can be recorded 

179 using transit, compass, azimuth wheel, clinometer, etc.

180 8.2.3 Measurement units can consist of metric or imperial units, but only one should be 

181 used for any single diagram.

182 8.2.4 Manual measurements can be recorded using any number of available 

183 measurement methods, including, but not limited to:
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184 8.2.4.1 Baseline

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189
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190 8.2.4.2 Triangulation

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194 8.2.4.3 Polar Coordinate

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196

197 8.3 Electronic Methods - The following list includes but is not limited to available electronic 

198 diagramming methods. Specific information and requirements on the use of these methods 

199 are outside the scope of this document.

200

201 8.3.1 Terrestrial LiDAR Scanning

202 8.3.2 Mobile Mapping

203 8.3.3 Photogrammetry

204

205 8.3.3.1 Aerial
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206 8.3.3.2 Terrestrial

207 8.3.3.3 Close-Range

208

209 8.3.4 Global Navigation Satellite System (GNSS)/Global Positioning System (GPS)

210

211 8.3.5 Total Station

212

213 8.3.6 Blended Methods

214

215 9 Output/Deliverables

216

217 9.1 Typically any of the above methods can be converted into any of these below types of 

218 deliverables. What output is created is likely to be driven by local protocols or policy.

219

220 9.2 Data may be processed through intermediate or proprietary software to reach the below output 

221 types. All data handling should adhere to local protocols for evidence handling and protection 

222 from data loss. The integrity of data procedures should be established.

223

224 9.3 For any output, it is the responsibility of the investigator to convey the following, at a 

225 minimum:

226

227 9.3.1 Measurement type (Metric or standard)

228 9.3.2 Legend

229 9.3.3 Key

230 9.3.4 Orientation of the scene to compass directions (ex. include a direction arrow, 

231 compass rose, or written description of direction)

232

233 9.4 Diagrams can be presented in various perspective formats based on the investigator's needs. 

234 Perspective diagram options include bird eye/floor plan, elevated, exploded, and 3-D.

235

236 9.5 Scale 2-D Diagrams

237 9.5.1 Computer Generated

238 9.5.2 Hand-Drawn

239

240 9.6 Computer-based output

241 9.6.1 2-D imagery or depictions of scenes

242 9.6.2 3-D imagery or depictions of scenes

243 9.6.3 Software-specific renderings of 2-D and 3-D environments

244
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245 9.7 3-D Printed Materials

246 9.7.1 Physical printed items from 3-D printers

247
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248 Annex A (Informative) References

249 ASTM E1020-13 - Standard Practice for Reporting Incidents that May Involve Criminal or Civil 

250 Litigation

251 Boots, Kent E., and Joel Salinas. Fundamentals of forensic mapping. Kinetic Energy Press, 2010.

252 "Guidelines for use of terrestrial LiDAR scanners in criminal justice applications." Forensic 

253 Technology Center of Excellence (FTCoE). Accessed October 4, 2022.

254 https://forensiccoe.org/guidelines_terrestrial_lidar_scanner/

255 Puente, I., H. González-Jorge, J. Martínez-Sánchez, and P. Arias. "Review of mobile mapping 

256 and surveying technologies." Measurement 46, 7, 2013, 2127-2145.

257

258 National Forensic Science Technology Center (U.S.). "Crime Scene Investigation." Bureau of 

259 Justice Assistance, U.S. Department of Justice, National Institute of Justice, NIST, NFSTC, 

260 2013.

261

262 American Society for Photogrammetry and Remote Sensing. "ASPRS Guidelines for 

263 Procurement of Geospatial Mapping Products and Services." Photogrammetric Engineering & 

264 Remote Sensing, July, 2014, 597.