As we traverse the threshold into the future, the pool building industry is not left behind. The constant evolution of technology and innovative design principles necessitate a redefinition of the industry's trajectory. The metamorphosis of pool building is being driven by a convergence of multiple factors, from the ecological to the technological and even sociological. In this article, we will delve into a rigorous analysis of the future of pool building, offering an exploration of the trends and predictions shaping the industry.

To begin with, having an understanding of the emergent ecological consciousness is intrinsic. The incipient shift towards sustainability in pool building is more than just a trend, but rather an indication of the future industry landscape. The notion of 'green pools' is gaining currency. These are pools that are harmonious with the environment, utilizing resources efficiently and reducing wastage. The application of solar heating and variable-speed pumps are prime examples of how this trend is materializing. Yet, it is important to note that these features also yield economical benefits due to the reduced costs of operation and maintenance. Here lies an elegant symbiosis between ecological sensitivity and economic prudence, which is a defining characteristic of the industry's future.

Next, the advent of smart technology has permeated into the pool building industry, and its influence is predictably going to augment. Automation is the watchword here. From automated pool maintenance systems that leverage artificial intelligence to monitor and adjust pool conditions, to smartphone apps that control lighting, temperature, and safety features, the role of technology in enhancing user convenience and experience is undeniable. Yet, an informed perspective would also acknowledge the trade-offs associated with this trend. While automation offers convenience, it is also accompanied by an increased susceptibility to technical glitches and cybersecurity threats. Pool builders will need to balance these factors while integrating smart technology.

Spatial considerations are also a crucial aspect of the shift in pool building. The traditional concept of pools as sprawling, rectangular structures is being replaced by a more flexible understanding. Compact pools, or 'spools', are gaining popularity, particularly in urban areas where space is a premium. The rise of this trend can be attributed to a blend of demographic shifts, urbanization trends, and the evolution of design philosophy. Yet, the smaller size of these pools does not imply a compromise on luxury or aesthetic appeal. Rather, it is a testament to the industry's ability to adapt and innovate in the face of changing circumstances.

In terms of design aesthetics, a postmodern approach seems to be the order of the day. Pool designs are bending towards a more organic, naturalistic look, often mimicking bodies of water found in nature. This trend can be understood in the context of the broader shift towards biophilic design in architecture and interior design. Not only does this add an element of tranquility and cohesiveness to the landscape, but it also seeks to foster a deeper connection between humans and their natural environment.

In conclusion, the future of pool building lies at the intersection of the ecological, technological, and sociological. It is an exciting domain of endless innovation and dynamic shifts. However, in this rapidly transforming landscape, it is essential for pool builders to stay informed, adaptable, and above all, committed to enhancing the user experience. The true measure of success in this industry will be the ability to seamlessly marry functionality with aesthetics, while maintaining a keen sensitivity towards the environment and the unique needs of the client. As we move further into the 21st-century, the future of pool building is bright, promising, and ripe with potential.