Terrain coming out as jagged spikes

[scottdog62 9]

I try import terrain form sat images and get terrain heightmap from open topo but when i create the mapframe it just comes out as jagged spikes.

I'v done the atlas tutorial and CAPTNCAPS online tutorial. Now trying to make my own map with imported terrain.

Any help? or other tutorials that can help me on my way?

[RoF 240]

Did you resize your heightmap? When you resize, you also have to the change the vertical height as well.

[scottdog62 9]

Did you resize your heightmap? When you resize, you also have to the change the vertical height as well.

 

I'm not sure I just followed CAPTNCAPS tutorial, used a heightmap from open topography, put it in QGIS, used "Stretch to current extent", then put it in gimp and matched it up with the sat image, exported as terrain.png and exported sat image as png as well and then made a made a mask image. Then made a map frame in Terrain builder.

 

One of them I made came out very hilly whilst the current I tried came out just as spikes.

Could you point us in the right way to make a heightmap?

[dragonsyr 21]

try open it with L3DT , smooth it there and then import to TB.

[scottdog62 9]

Guys really struggling with the height map, trying to use L3DT, but the hills always come out jaggered. I need help with getting and importing the height map.

[scottdog62 9]

This is what my heightmap looks like in L3DT

 

 

not sure why its underground

 

[RoF 240]

Maybe it's to do with exporting you heightmap as a .png? Cant you export it as an .asc file from QGIS and .png? Then keep the .asc file as your height map, then use the .png file to line up your sat image...

 

 

I used Global Mapper to do what I wanted, so I'm just guessing here :D

[HorribleGoat 1464]

I would guess the map size is scaled down?

I would say that usually this means only the X / Y coordinate scaling and the actual height is not scaled down with it. L3DT has operation "change vertical range" in Operations -> Heightfield which with you can change the range your map height is in.
For example you have 10x10km piece of height data with highest point lets say 800 meters and you scale the map down to 5x5km. It still has highest point of 800m so it will be spiky. Now you scale the heights too with the "change vertical range" and set the high point from 800 to 400 and your map should be quite like its supposed to be.