Perhaps you should try some spelling variations:
"modified lighting estimation algorithms" » "modified lighting estimation algorithm", "modified lighting optimization algorithms", "modified lighting optimisation algorithm", "modified caging estimation algorithms"
"modified invasive approximation algorithms" » "modified passive approximation algorithms"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified invasive approximation algorithms") OR ("modified lighting estimation algorithms"))~.
• Removing quotes may allow a broader search: (( modified invasive approximation algorithms ) or ( modified lighting estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified invasive approximation algorithms") or ("modified lighting estimation algorithms"))*.