Casting of 3-dimensional footwear prints in snow with foam blocks

Evaluation of an Innovative Casting Method in the Recovery of Footwear Impressions in Soil

“…With only photographs, an examiner would have limited views of the features. Making a cast of 3D impressions should be a regular practice, even in cases where photographed impressions appear to have limited details [5,[21][22][23] . The foam possesses positive features such as high dimensional and mechanical properties stability, ease of deformation and handling, making it an alternative material for the accurate reproduction of 3D footwear impressions.…”

“…Figure 5a displays a dense outer layer at the foam surface, with aw sizes decreasing to 100 µm, forming the basis of the casting design for recovering a 3D footwear impression. The dense surfaces of foam blocks are caused by the existence at the foam-impressions interface of a thin layer of noncellular polymer [19][20][21][22][23][24] . The uniformly distributed, typical closed-cell cross-section beneath the skin layer is shown in Fig.…”

Technological innovation in the recovery and analysis of 3D forensic footwear evidence: Structure from motion (SfM) photogrammetry

“…An SfM approach works across a range of substrates from traditional sand, mud, and soil, while also having potential for substrates that are often regarded as difficult to cast such as loose sand or snow [28,29,30,31,32]. Figure 8 illustrates this in the context of loose, sandy gravel found on a path on a local nature reserve.…”

A new method for the recovery and evidential comparison of footwear impressions using 3D structured light scanning

“…It has been noted generally that there is little substantive research investigating the most appropriate practice in the field (Battiest et al, 2016). Some substrates such as sand and snow can prove to be particularly problematic substrates to recover impressions from (Petraco et al, 2016), since sand is very fragile and snow melts during the exothermic reaction of the casting material. One approach to this has been to spray the impression with a fixative to highlight the detail before the dental stone can be poured in (Battiest et al, 2016;Houck, 2015), while another has been to use foam blocks (Petraco et al, 2016).…”

“…Some substrates such as sand and snow can prove to be particularly problematic substrates to recover impressions from (Petraco et al, 2016), since sand is very fragile and snow melts during the exothermic reaction of the casting material. One approach to this has been to spray the impression with a fixative to highlight the detail before the dental stone can be poured in (Battiest et al, 2016;Houck, 2015), while another has been to use foam blocks (Petraco et al, 2016). Both approaches demand physical intervention with the impressions which ultimately reinforces the notion that there is only one chance to recover an impression -regardless of how significant it is to the investigation.…”