*4.5. Parameters Analysis*

SSIN is constructed mainly by IIG. The number of IIG, *N*, and the number of RCAB in each IIG, *L*, are two key factors affecting network performance.

To explore the impacts of *N* and *L* on performance, we conduct eight groups of contrast experiments. In order to keep the number of parameters within a reasonable range, we adjust *L* from 1 to 4 with a step of 1 by keeping *N* = 3, then we adjust *N* from 2 to 5 with a step of 1 by keeping *L* = 2, while the other settings remain unchanged. The experiment is conducted on the WV2 test dataset. The objective evaluation indices results are given in Table 3. To obtain the influence of *N* and *L* on network performance more intuitively, we show the experimental results in Figure 6.


**Table 3.** The quantiative evaluation results with different number of IIG and RCAB on the wv2 test dataset. The best value is in bold.

We first discuss the effect of *L* with *N* fixed to 4. The purple curve in Figure 6 shows the experimental results, from which we can find that the SSIN performance and the number of parameters grow with the increase of *L*, especially when *L* increase from 1 to 2. However, the increase of *L* has little impact on network performance when *L* reaches 2, but brings more parameters. So for the rest of the experiment, the *L* is set to 2.

Then, we fixed *L* to 2 to study the effect of *N*, the results of this part are shown by the blue curve in Figure 6. As we can see, with the increase of *N*, the performance and the number of parameters of SSIN increase steadily, especially in Figure 6a,c. This is because the number of IIB grows as *N* increases, and information interaction can enhance the performance of the SSA module and significantly improve the final information fusion performance, as we discussed in Section 4.4.

In addition, it is worth noting that increasing *N* can bring greater performance improvement than increasing *L* under the condition of a similar number of parameters. The main reason is that increase of *L* can enhance the ability of information extraction but hinder the dissemination of information, while the increase of *N* can significantly increase the number of information interactions. The interaction between spectral information and spatial information has a more important impact on the performance of SSIN.

To sum up, considering the performance and the number of parameters, we selected *N* = 4 and *L* = 2 as our final setting for our proposed SSIN.
