You have several options:
In the "Calculate distance" tab:
Option 1: Click any odorant on the map, and it will be assigned as "Odorant 1". Click a second odorant, and it will be assigned as "Odorant 2". Their distance will appear in the gray windo at the upper right hand side.
Option 2: Select an "Odorant 1" from the pull-down menue (use either CAS, CID or smell). Select an "Odorant 2" from the pull-down menue (use either CAS, CID or smell). They will appear color-coded in the map, and their distance will appear in the grey windo at the upper right hand side.
In the "Choose multiple points" tab:
Option 1: Click sequentially on as many points as you would like to include in your group.
Option 2: Sequentially select an "Odorant 1" from the pull-down menue (use either CAS, CID or smell). Each odorant selected will be added to the group.
Option 3: You can choose a pre-selected group from the pull-down menue.
In all cases, once you have selected your set, you can both download all the pairwise distances by downloading the data file, and download a figure of your selected odorants in OdorSpace by downloading the figure file.
Note that you can click the left button and mark an area to zoom.
The data set contains 144 odorants from Dravniek's atlas of odor character profiles . Their perceptual descriptors are reduced to 4 dimensions by principal component analysis (PCA) and their first two principal components are displayed here. When two odorants are selected the euclidean distance between their coordinates is displayed. This distance corresponds to the perceived similarity of the odorants, see Khan et. al., 2007.