Hello, I am using ArcGis 10.2.1 and I need to download the extension "Segmentation and Classification toolset", which belongs to spatial analyst tools in ArcGIS. And, I don't know if this extension can be used in ArcGIS 10.2. Thanks for the help and info.
Go to customize, Extensions... toggle on the spatial analyst extension.
Start Arctoolbox, expand the Spatial Analyst toolset... is the toolset there? You don't have to 'download it', it either existed in 10.2.x or it wasn't available then. Here is the 10.5 help topic in any event and it existed in 10.3 at least (edited to highlight the 10.3 in case you missed it)
"Segmentation and Classification" toolset was added to ArcMap in ver. 10.3.
What's new in ArcGIS for Desktop—Help | ArcGIS for Desktop
You need to upgrade ArcGIS Desktop, in order to avail the "Segmentation and Classification" toolset.