## 3 Results  
Images from the two surveys produced very different images of the same areas. The images from August 2019, mostly, are indistinct in some areas and do not provide much clarity, while the images \begin{table}
\begin{tabular}{c c c} \hline
**Conditions** & **Survey in August 2019** & **Survey in February 2020** \\ \hline Ambient Temperature & 23 \({}^{\circ}\)C & 30 \({}^{\circ}\)C \\ \hline Exterior Temperature & 25.5 \({}^{\circ}\)C & 32.7 \({}^{\circ}\)C \\ \hline Relative Humidity & 96\% & 50\% \\ \hline No. of Days after Rainfall & 0 & 14 \\ \hline Typology of Day of Survey & Overcast day & Sunny day \\ \hline \end{tabular}
\end{table} 
Table 1: Environmental parameters mapped for the thermal surveys. the thermal survey. Yet, it shows that the effects of the infiltration are still very much visible. It is the contrast with which the infiltration is visible that is the cause for discussion here. The images show clear distinction in the level of detail of the anomaly observed and smallest dissimilarity on the target surface. One of the largest inferences made on this site versus prior studies was the large influence of Relative Humidity and the external temperature of the building on the imaging. This site being located in a tropical wet and dry climactic zone has high humidity when compared with temperate zones. Good IR images depend on the ability to acquire high contrasts in temperature between materials. This temperature contrast, or delta T, produces well-defined images that permit researchers to identify clear distinctions in images particularly at the vault junctions above. The function of relative humidity in thermal imaging has been well-documented; high humidity reduces the surface evaporation of moisture from building materials. Water intrusion in porous materials change the thermal properties of the material itself. Therefore, the difference of temperatures between the wet and dry areas is minimized when the fluid flux is lowered due to high relative humidity [5, 12, 15, 26]. Consequently, this reduction in fluid flux lowers the contrast available in thermal images and degrades their quality. Moreover, the evaporation flux occurring on the surface of porous materials cools the surface, up to 2 \({}^{\circ}\)C-3 \({}^{\circ}\)C. This change of the temperature, where the evaporation flux occurs, is clearly detectable by IRT. However, in this case, the surface is directly heated especially where the heating is not even (the surface temperature ranging more than 10 \({}^{\circ}\)C), the effects of cooling due to the evaporative flux are not detectable. There are several standards developed to aid in thermal surveys and related imaging in broad and general terms. This study in India, particularly in Hyderabad, shows that there are some variables that can also impact the imaging process, and need to be considered for making a holistic approach to passive thermal imaging, especially in tropical climates. Based on this, we propose a modest rubric by which we can judge the efficacy of employing IRT at a site in different months in Hyderabad, see Figure 5. This rubric leans on the above-mentioned standards, as well as from our experience [23, 24]. Moreover, year round temperature and relative humidity data for Hyderabad come from the Meteorological Department of India. Based on ASTM Standard C1060, we can see that the ideal imaging temperatures result in a delta T between internal and external surface temperatures of 10 \({}^{\circ}\)C, which is the difference in temperatures between the internal surface to image, and the surface temperature of the exterior of the structure. Temperature gradients lower than this result in degraded imaging conditions due to the formation of misrepresentations in the images. These errors lead to inconclusive imaging and leave room for errors in image interpretation.