Knowledge is power — and, in Ascension Parish, it apparently also means a lot more tax revenue for local government.

With a trove of new data collected earlier this year through an aerial imagery project, new electronically submitted building permits and an updated website, Ascension Parish Assessor M.J. “Mert” Smiley Jr. is adding existing, unreported properties onto the tax rolls.

Tax bills won’t go out until later this year, but preliminary figures show the total taxable assessed value in Ascension — the assessed value minus items like homestead exemptions — increased 10.7 percent between 2013 and 2014, from $1.04 billion to nearly $1.15 billion.

Smiley and his chief deputy, Justin Champlin, said the projected increase is estimated to mean about $11.5 million in additional tax revenue for the parish School Board, Sheriff Jeff Wiley and other local governments.

After assessment notices went out early last week, Smiley started the “open book” period Friday for the 2014 tax roll. Property owners can review their assessments on the office’s upgraded website and discuss them with his staff. The period ends Aug. 29.

Smiley, a former two-term Republican legislator who took a tough line on taxes in the House, said Thursday that some calls have started to come about the 2014 tax rolls.

“We treated everybody fairly and equitably. It’s only fair to the 85 percent that have been paying, that the 15 percent that were not on the books (now) pay their fair share. That’s as simple as I can put it, but they will be treated fairly and equitably,” Smiley said.

Smiley, who is in his first term as assessor, won the seat in a close October 2011 election after a tough campaign in which he accused then-Assessor Renee Mire Michel, a Democrat, of playing favorites and leaving a sizable percentage of properties off the rolls.

The two made peace after the campaign, and Michel welcomed Smiley into her office during the long overlap period before Smiley took office in early 2013. But Smiley said he used the time to assess operations in Ascension and elsewhere and figure out how to approach the unreported properties.

Smiley said he first created a “sections program” to estimate how much property was not on the books. The program found about 14 percent to 17 percent of the property was not on the books.

He attributed the past data problems to a lack of manpower. Champlin said the assessor’s office had received a stack of paper building permits from the parish once a year. Smiley said limited staff had to track down improvements reflected in each permit but would fall a little behind each year.

Smiley said his office has reached an agreement with parish government to receive permits electronically and continuously, so the assessor’s office won’t fall behind again.

Also, starting in the second half of 2013, Smiley went to the School Board, Parish Council and other local governments asking them to share the $400,000 cost to hire the firm Pictometry to conduct aerial imagery. Smiley also got a $150,000 federal grant from the Delta Regional Authority.

Champlin said the flights gathered images in much higher detail than the images the assessor had from a multi-parish program in 2010.

Pictometry was able to generate about 22 pictures for each structure, Champlin said. A computer filtered out the best pictures, giving the assessor not only overhead shots but also “oblique” images so the sides of homes could be seen and measured. The side images allow distinctions to be made between actual living area and carports or porches.

Smiley also hired Apex, which used the images to sketch every improvement in the parish by July.

“This technology is what allowed us to find the new improvements, and we found quite a few of them,” Smiley said.

He said the imagery matched up with the earlier 14 percent to 17 percent estimate of properties off the rolls.

The imagery is also now on the assessor’s website. A simple name or map search can turn up properties with multiple aerial and ground-level images, a rundown of ownership and tax information and other data.

The increase in the taxable assessed value from 2013 to 2014 is midway through the once-every-four-years reassessment cycle in Louisiana. Large increases are typically seen in reassessment years. Smiley and Champlin attributed the increases this year in taxable values — and resulting tax revenue increases — to the data-gathering effort.

The 2013 tax year was the first time the rolls broke $1 billion in taxable assessed value and came after an initial sweep of unreported properties, but before the over-flights this year. That work generated an additional $10.85 million in tax revenue, Smiley said.

In Louisiana, property owners’ tax bills are calculated by applying millage rates, which various governments set annually, to an assessed value, which the assessor determines.

The assessed value is based on a percentage of a property’s market value. Residential property is assessed at 10 percent of market value. Commercial buildings are assessed at 15 percent of market value.

Smiley is expected to certify the tax rolls on Sept. 2. Appeals are due Sept. 11.

His website is at www.ascen

Follow David J. Mitchell on Twitter at @NewsieDave.