Virtual Herbarium
The virtual herbarium allows on-line access to (label) data originating from collections kept at the NHN. The NHN started digitising label data in 1997. At present (spring 2009) label data for over 1,000,000 collection sheets have been digitised. Besides digital images have been made of some 180,00 sheets and another 85,000 labels. Data and images are made available on internet through the NHN website (BRAHMS Online; to be implemented july-august 2009) as well as via the GBIF portal (GBIF ).
- Introduction
-
Digitisation of information/data found on labels of herbarium specimens started in 1997 at the NHN in the so called “Types” project. At present digitisation is part of ongoing collection management activities. Recently a first PhD has been completed based on herbarium records (Raes, N., 2009.Borneo. A quantitative analysis of botanical richness, endemicity and floristic regions based on herbarium records. - Nationaal Herbarium Nederland - 144 pp).
- Methods
Digitisation of herbarium specimens includes both text and images.
Label text and information has been electronically registered using BRAHMS (Botanical Research and Herbarium Management System). BRAHMS is written in Visual FoxPro, being developed by the Department of Plant Sciences, Oxford and used by projects and herbaria worldwide. The National Herbarium Nederland has developed a protocol for data entry aiming at maximising consistency in data entry between people and through time.
Between 1997 and 1999 digital images were taken with a Leaf Lumina digital scan camera at a maximum resolution of 300 dpi. Files were saved in JPG-format and named after the barcode of the respective sheet. Because of the fixed camera and computer set-up (no need to re-focus after every herbarium sheet) no images were taken of most non-Phanerogam groups like Fungi, Musci and Algae. Image files were copied to CD. Prior to the Web presentation, using a macro, each image file was reduced to a thumbnail-size image (10-15 KB) and an image of 140DPI (40-250 KB) which still allowed the viewer to read label data. The link between the image file and the data lies with the barcode. A similar procedure has been followed after 2000 when the Leaf Lumina was replaced by a Nikon D100 digital camera. This camera also produced images with a maximum resolution of 300 dpi. From 2004 onwards images were also made using a Herbscan which produces 600 dpi images.
