In this manuscript we present a focus stacking system, composed of commercial photographic equipment. The system is inexpensive compared to high-end commercial focus stacking solutions. We tested this system and compared the results with several different software packages (CombineZP, Auto-Montage, Helicon Focus and Zerene Stacker). We tested our final stacked picture with a picture obtained from two high-end focus stacking solutions: a Leica MZ16A with DFC500 and a Leica Z6APO with DFC290. Zerene Stacker and Helicon Focus both provided satisfactory results. However, Zerene Stacker gives the user more possibilities in terms of control of the software, batch processing and retouching. The outcome of the test on high-end solutions demonstrates that our approach performs better in several ways. The resolution of the tested extended focus pictures is much higher than those from the Leica systems. The flash lighting inside the Ikea closet creates an evenly illuminated picture, without struggling with filters, diffusers, etc. The largest benefit is the price of the set-up which is approximately € 3,000, which is 8 and 10 times less than the LeicaZ6APO and LeicaMZ16A set-up respectively. Overall, this enables institutions to purchase multiple solutions or to start digitising the type collection on a large scale even with a small budget.

We tested five 3D digitization systems and one method of 2D+ recording on one object: a human skull from the Royal Belgian Institute of Natural Sciences collection (RBINS). We chose a skull because it has both simple and complex structures and different materials such as bone and enamel within the same object.The results obtained with the different technologies were compared for 3D shape accuracy, texture quality, digitization and processing time and finally price.Our results show that the structured light scanner provided the best results to record external structures, CT was found to be the best to record internal structures and is also the best for recording reflecting material such as enamel. Photogrammetry is a very good compromise between portability, price and quality. RTI is a method of 2D+ recording and is a complementary technique, using the same equipment than photogrammetry, which can capture small morphological features that are not easily digitized with the 3D techniques.

Digitising a collection is key to make it last even after the physical objects are no longer available. Almost all of the techniques currently available to digitise a natural history collection in 2D+ and 3D are listed herein. The techniques are explained in a way that even one without any knowledge on the subject may understand their principle. The strong and weak points of the techniques are discussed, and an overview of suitable collections and specimens are given for each one of them. Also, plenty of examples already digitised with each technique are provided together with the links to visualise them in 3D. After explaining all the different digitisation options, the subsequent chapters provide information on how to improve the 2D+ and 3D digital twins of the specimens and techniques are compared to each other by means of test specimens. These give a fast overview of the capabilities of the digitisation techniques. Possible solutions to avoid digitisation errors are equally provided. Lastly, the dissemination of the results and the data management of the 3D models are briefly discussed in the final chapters. Also, a large chapter is provided with several workflows that can be followed to get the best possible results.

No abstract