| Sun Aug 8 15:24:35 2021 by map maker |
| It would be nice to know what is the altitude of the land is. There is colours to help us but when my map use the Olsson colour map, what is the difference of height between 2 colours ? |
| Mon Aug 9 06:15:44 2021 by Mizuki |
| You can probably use an eyedropper tool and compare it to the color definition file. |
| Mon Aug 9 13:08:15 2021 by Torben |
| Internally, altitudes typically go from -0.1 to +0.1 (for historical reasons), with 0 being sea level. The "water line" value is added to all altitudes to change sea level. A very rough translation to altitudes is 0.1 == 10km, so multiply the internal value by 100 to get km. Different colour maps use different numbers of colours, so there is no simple relation between colours and altitudes. The last colour in the colour map is for altitudes of 0.1 or higher, and sea level is (number of colours)/2+3. The Olsson map has 66 colours, so sea level is 36. This leaves 30 colours for altitudes between 0 and 0.1, corresponding to 0 to 10km. So one colour difference is approximately 333m. For other colour maps, this is different (since they typically have more colours, one colour difference is less). Note that the above applies only if you do not modify colours by latitude. |