To get accurate and complete information about buildings in OpenStreetMap, you have to complete its atributes infomation correctly. These are the following steps :
1. Make building polygon using draw node menu, in the left side of menu bar
2. In order your polygon easy to recognize as a building, click Presets > Man Made > Man Made > Building. If you succeeded, your polygon would be highlited with brown color like picture above, then in properties box in the right side of JOSM there is Key as a ‘building’ with ‘yes’ value. That mean JOSM has been recognize your polygon as a buidling.
4. The next step is give information such as building name to the building that you edit. on Properties box click +Add button and new window will show up to change value of the building. In Please select a key, choose ‘name’ land in Please select a value type name of the building. Click OK. If you done, the box properties in the right side of window you will see there is a new information about the name of the building.
5.Now it is time to add building attributes that contain important information about building structure. Click Preset > Building (or Bangunan). There will be a window show up and it contains list of information about building such as Building Function, Building Strucutre, Type of Wall, Type of Roof and ngsi Bangunan, Struktur Bangunan, Tipe Dinding, Tipe Atap, and Number of level with its options. Choose atributes according to the real condition of the building.. Then click Apply Preset. After that, the information will be added in properties box.
6. Do not forget to save your data if you want to continue your work offline, and upload it when you connect to the internet.
7. Happy mapping! 😀