The pan-European Very High Resolution (VHR) Image Mosaic 2021 is a seamless mosaic of the VHR 2021 dataset.

The input data consists of a mix of Pleiades, SuperView, Worldview, Kompsat-3, Kompsat-4, Geoeye, SPOT, Deimos-2, Vision-1 and TripleSat images. To enhance the appearance of the input imagery, a histogram stretch was applied, cutting off the lowest and highest 0.1 percent of the histogram values and stretching the remaining values to fit the 16-bit pixel depth. For each input image, only selected areas were used to create the mosaic, and the rest was masked out to exclude areas with clouds and their shadows. Color balance was achieved using a second-order method, which modifies all input pixels toward a set of multiple points derived from a two-dimensional polynomial parabolic surface, ensuring a seamless mosaic.

For several water bodies, especially large lakes, the final result exhibited a patchy surface pattern due to presence of sun glint on the satellite images. A post-processing methodology was implemented to recalculate the digital values to produce a seamless appearance surface of some of these major lakes: Vänern and Vättern (Sweden), Oulu (Finland), Peipus (Estonia), Geneva (Switzerland/France), Constance (Switzerland/Germany/Austria), Garda and Bolsena (Italy), Skadar (Montenegro/Albania), Prespa (North Macedonia/Albania/Greece), Beysehir, Iznik and Van (Turkey). The applied methodology consisted of creating individual mosaics with the images comprising only the mentioned lakes (a mosaic per lake), calculating Normalized Difference Vegetation Index (NDVI) for shoreline extraction, and color balancing each mosaic individually with all land surfaces masked out, using only pixels belonging to the water category. This approach allowed smoothing the patchy surfaces of the above-mentioned lakes considering statistics solely from the water pixels, ensuring a more uniform appearance.

To enhance the visualization of the entire dataset at larger scales (greater than 1:500.000), the mosaic displays pan-European overviews generated from the pan-European Very High Resolution 2018 Image Mosaic. The updated VHR 2021 version is visualized only at scales below 1:500.000.

The mosaic primarily is used as input data in the production of various Copernicus Land Monitoring Service (CLMS) datasets and services, such as land cover maps and high-resolution layers on land cover characteristic. It can be also useful for CLMS users for visualizations and classifications on land.

The input imagery for the creation of the mosaic is provided by ESA. Due to license restrictions, the VHR Image Mosaic 2021 is only available as a web map service (WMS), and not for data download.