On 28-05-2020 13:30, Nicolas Cadieux wrote:
Hi,

Hi Nicolas, thanks for pointing this out!


I see many people have responded exactly to your question so I have a question 
for you. I am playing the devil’s advocate.  What are your classification?  Can 
any of this be classified any other way than manually? You could save time if 
you could preclassify building and only check the results manually?  Can size, 
shape, or colour help?  Can you use another data base like a city map or sensor 
data help?  Can you use satellite images to do some preclassification?  Have 
you thought of using AI with aerial photography?

Yes we have been thinking of automating this, but we don't think it is possible. We are interested in the roof construction material and in case of certain material, if the roof is damaged or not.

As we are not interested in overall statistics but in the actual roof state of houses (cause those people might get money to fix their roofs) we will need to manually check them all.

Satellite imagery was not detailed enough, so a (slow) drone will be used for mapping the area in high resolution. This will take days or even weeks. In my experience the colours and quality differs per flight (due to the weather and sun angle) making AI learning very hard.

Luckily we have many hands around and can split the task! My job is to make this as easy as possible, in QGIS


If not, can you build a tool that will permit you to select multiple buildings 
at a time and only enter the information once?

Yes, that was the 2nd step. It could also be some kind of tool that works like a highlighter. Just pick the "red" one from a list and start clicking all the damaged buildings. That would even mean only 1 click per building.

Or, more generic, an edit tool where you can choose the field and the value to set, and start clicking. I think I'm developing a new plugin idea here!!


Nicolas Cadieux
Ça va bien aller!

Le 28 mai 2020 à 02:33, Raymond Nijssen <r.nijs...@terglobo.nl> a écrit :
Does anyone know if there is a tool in QGIS to quickly classify features 
manually?

I have a layer with 17,000 buildings, all need to be set to 1 of 5 values. I'm 
thinking about making a (quick and dirty) plugin that:

- On clicking the building shows a popup menu with the 5 choices
- Clicking the choice would update the value and change the color (redraw)

Every click less really counts here. I already set up a form widget but also 
having the location of the menu near the building polygon is way more 
efficient. (I mean, no need to cross the screen with your mouse cursor.)

Thanks!

Raymond
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