Wedge of missing data reprojecting to stereographic

Question

I am trying to reproject an equirectangular projection image into stereographic around the north pole of mars using gdalwarp and I am not sure what is happening in my output image.

The input image is a normal looking rectangular image with no black regions. Zooming in to the missing wedge region I can see that not all of the pixels from the input image are present in the output image.

My gdalwarp command:

gdalwarp map_upper_crop.tif map_north_pole.tif -t_srs "+proj=stere +lon_0=0 +lat_0=90 +a=3396200 +b=3376200 units=m"

gdalinfo output on the input image:

Driver: GTiff/GeoTIFF
Files: projection_space_basemap_top.tif
Size is 11520, 1035
Coordinate System is:

PROJCS["unnamed",  
    GEOGCS["unnamed ellipse",  
        DATUM["unknown",  
            SPHEROID["unnamed",3396200,169.8100000000004]],  
        PRIMEM["Greenwich",0],  
        UNIT["degree",0.0174532925199433]],  
    PROJECTION["Equirectangular"],  
    PARAMETER["latitude_of_origin",0],  
    PARAMETER["central_meridian",0],  
    PARAMETER["standard_parallel_1",0],  
    PARAMETER["false_easting",0],  
    PARAMETER["false_northing",0],  
    UNIT["metre",1,  
        AUTHORITY["EPSG","9001"]]]  

PROJ.4 string is:
'+proj=eqc +lat_ts=0 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +a=3396200 +b=3376200 +units=m +no_defs '
Origin = (-10669477.099999999627471,5334738.599999999627471)
Pixel Size = (1852.339774305555466,-1852.339791666666542)
Metadata:
AREA_OR_POINT=Area
TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
TIFFTAG_XRESOLUTION=1024
TIFFTAG_YRESOLUTION=1024
Image Structure Metadata:
INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left (-10669477.100, 5334738.600) (179d59'59.99"E, 90d 0' 0.01"N)
Lower Left (-10669477.100, 3417566.916) (179d59'59.99"E, 57d39'22.50"N)
Upper Right (10669477.100, 5334738.600) (179d59'59.99"W, 90d 0' 0.01"N)
Lower Right (10669477.100, 3417566.916) (179d59'59.99"W, 57d39'22.50"N)
Center ( 0.000, 4376152.758) ( 0d 0' 0.01"E, 73d49'41.26"N)

Any idea what is going wrong here?

Answer 1

I was able to get the correct output by adding the following options to my gdalwarp command:

-wo sample_grid=yes, -wo sample_steps=1000, -wo source_extra=2 -wo CUTLINE_ALL_TOUCHED=true -r cubic

Thank you user30184 for pointing these out!