Removing black lines between merged tiles?

Question

I merged several rasters, but there is a problem with lines between sheets.

Raster is created from LiDAR datasets. Rasters were produced from different datasets via this application: https://iaps.zrc-sazu.si/en/rvt#v and then merged.

For merging I used Raster > Miscellaneous > Merge in QGis 2.18.15.

Please see snapshot of a problem:

And the Merge function pop-up:

I found that even between unmerged sheets there is some minimal space:

How do I get rid of those lines?

Probably the original sin is already in the input.

Answer 1

It is possible that the black lines are pixels with missing data (no data). In this case, some options are:

• i) start over by accessing the raw point cloud data and generate a DEM with a method that process tiles altogether so to avoid having edge's artifacts. Take a look at Merging multiple LiDAR (.las) files?.
• ii) interpolate (fill in no data values) while keeping same resolution. There are plenty of methods and tools for this. See for example, Interpolate smoothly nodata values in QGIS and How to fill gaps in SLC-Off Landsat 7 ETM+ Images with QGIS?
• iii) resample (which is also interpolation) to a coarser resolution. See Deciding what interpolation method to use for resampling raster data? and Pros and Cons of using Bilinear Interpolation and Cubic Convolution when dealing with DEMs?.