## 1 Introduction
One of the best known is IsGISAXS [23], aimed at the analysis of different types of islands supported on a substrate. It supports different ordering types of islands, from random distribution via paracrystal, to fully ordered systems. Another frequently used platform is NANOCELL [24], which enables the simulation of 2D diffraction patterns from single-crystals for GISAXS/GISANS geometry. Further, FitGISAXS contains models for the description of GISAXS for monodisperse, polydisperse, and interacting particles with various size distributions, form factors, and structure factors [25]. HipGISAXS is suitable for the treatment of a wide range of structures, shapes, or morphologies, including multilayered polymer films and nanoparticles on top of, or embedded in, a substrate or polymer film layers [26]. DPDAK is a software for the processing and reduction of large amounts of data from synchrotron scattering experiments [27]. It also contains tools for calibration and correction of raw data, one- or two-dimensional integration, and the fitting and further analysis of the data, including the extraction of certain parameters. The most recently developed software is BornAgain, an excellent software for the simulation and fitting of X-ray and neutron reflectometry, off-specular scattering, and grazing-incidence small-angle scattering (GISAS) [28; 29]. This platform includes most of the options available in IsGISAXS, along with many new features. BornAgain has a very appealing user-interface and it is, being fairly generic, usable for scientists from different disciplines. Although currently existing platforms can be used to extract some important features of the 3D assemblies of NPs produced by self-assembly processes, they lack detailed analysis of the NP ordering properties. As stated above, and also discussed in Ref. [20], the NP ordering properties, or more precisely, the type of deviations of the NP positions from the ideal ones, can differ in various spatial directions in the same material. This fact strongly influences the GISAXS intensity distribution, and simulating the intensity distribution by the improper models usually results in incorrect structural parameters, even if the simulated GISAXS map agrees well with the measured one. All things considered, the current software options provide many options, but they are not detailed enough for suitable analysis of the materials based on 3D-ordered NP lattices, nor for specific core-shell structures with the displaced core-shell origins. In this paper, we present the software platform GisaxStudio for the analysis of thin films consisting of 3D lattices of NPs produced by self-assembled growth or ion-beam irradiation [31]. This software is a result of GISAXS data analysis and suitable model formulation of the aforementioned thin films that has been developed over the last 20 years. It enables the analysis and fitting of 2D GISAXS intensity distributions from 3D NP crystals, 3D lattices of NPs having spheroidal or core-shell shape, and from the NP arrays formed within ion-beam tracks. By fitting of the entire 2D GISAXS map, or even some of its parts, the GisaxStudio enables the determination of the NP's shape, size, and 3D arrangement properties, including the crystal lattice parameters and disorder type along each of the basis vectors of the 3D lattice. It is also possible to determine statistical distributions of all these parameters. The software includes theoretical models published in [20; 21; 22], which take into account the NP ordering properties along each of the basis vectors of the 3D NP lattice. The models and the software are already successfully applied in the GISAXS analysis of many systems, including 3D NP lattices [5; 7; 8; 9; 11; 13; 20; 21; 32; 33; 34; 35; 36] and NPs formed within ion tracks [22; 37; 38; 39], where fitting of the full 2D measured map was performed. We show how the platform is constructed, reveal its main features, and demonstrate its performance. The process of preparation for fitting and its main steps are demonstrated.