-2

I managed to make my slope map for a school project, in what is supposed to be percent, but how do I make the values make any sense? I need a legend where I classify the different values in 0-5%, 5-10%, 10-20% and 20-30% and 30 and above % and give those values different colors.

enter image description here

This is what I've done so far:

In my first thread I was told I have to reclassify my slope map and was linked here:

How to reclass a raster with reclassify grid values in QGIS?

I tried follow this but I really didn't get far. When using the values he did my map just got black, with some small with dots.

Improve this question
2
  • 1
    Welcome to gis.stackexchange! Please note that a good question on this site is expected to show some degree of research on your part, i.e. what you have tried and - if applicable - code so far. For more info, you can check our faq.
    – underdark
    Commented Nov 18, 2016 at 22:17
  • Remember that percentages are hundredths, so you may have a unit conversion issue. Look at the raster statistics to verify units.
    – Vince
    Commented Nov 19, 2016 at 2:01

1 Answer 1

Reset to default
2

Download plugin named Slicer. It's very easy to use.

Select input image, set output filename, select Variable and add initial and end value, click add to aggregate interval as a class, then finish with Slice button.

enter image description here

After executing the process, go to Properties(right click on your output raster in Layers panel) and go to Style and select Singleband pseudocolor, you can check the steps to apply a color palette in QGIS documentation.

The result could be something like this (DEM from a very mountainous area):

dem

PS: Don't forget to set legend values.

Improve this answer
5
  • Thank you so much for your answer. I have some more questions; In the Slicer-plugin the maximum value was set to 4,9 after executing "slice", I suppose I have to convert some values? This is how things looked after I used Slice; Image 1 And this is how things looked after I tried adding the values; Image 2
    – Mike_Nor
    Commented Nov 19, 2016 at 11:51
  • Don't worry, follow the link that I put in my answer to apply colors in your classification. In your case color black /gray goes from 1 up to 4, 5 is white. Use information tool to evaluate pixels in white areas and check what I said.
    – aldo_tapia
    Commented Nov 19, 2016 at 12:23
  • Thank you again, I really aprecciate the help. So, now my problem is that even though I choose the low areas to be purple, and the higher ones to be green, the map just looks all purple. Image What am I doing wrong this time? Clearly I'm really overlooking something obvious it feels like.
    – Mike_Nor
    Commented Nov 19, 2016 at 13:17
  • Did you look raster values? Clases from Slicer has integer consecutive values. Class number 1 (0-10%) has value of 1, class number 2 (10-20%) has value of 2, and so on. So, you need to set colors by integer number, and in label write the class description (i.e: 0-10%)
    – aldo_tapia
    Commented Nov 19, 2016 at 13:36
  • Ok, I think I got it now. Does this look correct to you? Image Thank you again for taking the time to answer.
    – Mike_Nor
    Commented Nov 19, 2016 at 17:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.