A method for filling invalid regions of terrain elevation model data, comprising: obtaining an isolated invalid grid in first terrain elevation model data, wherein the invalid grid is a grid without a valid elevation value; interpolating an elevation value of the isolated invalid grid by using elevation values of valid grids around the isolated invalid grid, to obtain data-interpolated first terrain elevation model data; obtaining invalid patches in the data-interpolated first terrain elevation model data, wherein each of the invalid patches is a region consisting of at least two adjacent invalid grids; and interpolating elevation values of the invalid grids in the invalid patches by using a further terrain elevation model data other than the first terrain elevation model data, to fill the invalid regions of the first terrain elevation model data, wherein the interpolating the elevation values of the invalid grids in the invalid patches comprises: obtaining valid grids around each of the invalid patches, to build an interpolation model based on the obtained valid grids and the invalid grids in the invalid patches; determining elevation differences of the valid grids in the interpolation model, wherein, the elevation differences of the valid grids are difference values between elevation values of the valid grids in the first terrain elevation model data and elevation values of the valid grids in the further terrain elevation model data; calculating elevation differences of the invalid grids in the invalid patches based on the elevation differences of the valid grids; and determining the elevation values of the invalid grids in the first terrain elevation model data based on the calculated elevation differences of the invalid grids and elevation values of the invalid grids in the further terrain elevation model data. obtaining an isolated invalid grid in first terrain elevation model data, wherein the invalid grid is a grid without a valid elevation value; interpolating an elevation value of the isolated invalid grid by using elevation values of valid grids around the isolated invalid grid, to obtain data-interpolated first terrain elevation model data; obtaining invalid patches in the data-interpolated first terrain elevation model data, wherein each of the invalid patches is a region consisting of at least two adjacent invalid grids; and interpolating elevation values of the invalid grids in the invalid patches by using a further terrain elevation model data other than the first terrain elevation model data, to fill the invalid regions of the first terrain elevation model data, wherein the interpolating the elevation values of the invalid grids in the invalid patches comprises: obtaining valid grids around each of the invalid patches, to build an interpolation model based on the obtained valid grids and the invalid grids in the invalid patches; determining elevation differences of the valid grids in the interpolation model, wherein, the elevation differences of the valid grids are difference values between elevation values of the valid grids in the first terrain elevation model data and elevation values of the valid grids in the further terrain elevation model data; calculating elevation differences of the invalid grids in the invalid patches based on the elevation differences of the valid grids; and determining the elevation values of the invalid grids in the first terrain elevation model data based on the calculated elevation differences of the invalid grids and elevation values of the invalid grids in the further terrain elevation model data. obtaining valid grids around each of the invalid patches, to build an interpolation model based on the obtained valid grids and the invalid grids in the invalid patches; determining elevation differences of the valid grids in the interpolation model, wherein, the elevation differences of the valid grids are difference values between elevation values of the valid grids in the first terrain elevation model data and elevation values of the valid grids in the further terrain elevation model data; calculating elevation differences of the invalid grids in the invalid patches based on the elevation differences of the valid grids; and determining the elevation values of the invalid grids in the first terrain elevation model data based on the calculated elevation differences of the invalid grids and elevation values of the invalid grids in the further terrain elevation model data.