How do I get rid of this thin band between raster layers created from TNM?

Question

After hitting my head against the table for many days, I'm humbly presenting myself to the QGIS community.

I downloaded 4 IMG files (1/3 arc second, elevation data) from The National Map on the USGS website. I then loaded these into QGIS v 2.4 and went through the following steps with each section.

First, I converted the raster from meters to feet using the Raster Calculator (outputting to a GEOTiff file and using the current layer extent).\

Next, I used the DEM(terrain models) tool to create a hillshade raster layer.

I'm assuming my adding of contours doesn't matter.

Why is there a line that forms between the sections? The data is supposed to be seamless between the layers.

Also, my Project CRS is NAD83.

Answer 1

The line might be from rounding issues when converting from meters to feet.

For the error in Hillshade creating, try to change the datatype from integer to float with gdal_translate:

gdal_translate -ot Float32 src_dataset dst_dataset

You can do that in QGIS too with Raster -> Conversion -> Translate, using the command line box in the form. Maybe it is even possible to run the raster calculator successfully after that step.

Answer 2

So, it looks like if when I create my hillshade layer using the DEM(terrain models) tool, I need to click "compute edges". This seems to take care of the problem, at least for that layer.