Photometrics

Some appraisal sketch software programs (like Apex and Rapid Sketch) now come with a built-in "Photometics" feature.  The feature allows an appraiser to import a drawing or an aerial photograph and then after establishing a known distance for scale it will provide the approximate distances for other lines (or walls) that you draw in the sketch program.  I have found the feature to be quite useful since it is less likely that as an appraiser I will make a significant mistake in an appraisal report regarding lot size or improvement size if I quickly confirm them using Photometrics.

Appraiser sketches are not meant to perfect.  In fact many appraisers, like many County Assessors, round their measurements to the nearest foot.  So 10.4' feet ends up being 10' feet and you are often going to be off by a percent or two when you calculate site or building area just because of this rounding.  For those appraisal purists who think they are bringing in their sketches with an accuracy down to 0.10' feet, I hate to burst your bubble but there are many buildings that are off just because they were not built perfectly square, and using a square grid or a sketch program that defaults to 90 degree corners is again introducing error.  The fact of the matter is that 5 appraisers who measure the same property will likely provide a client with 5 different building areas after they measure it.  Thus the measurements are not "precise" since they can not be exactly replicated while they may all be relatively "accurate" to within a few percent of the true measurement distance or the true area.

The Photometrics feature that is built into some appraisal sketch programs is very useful when lots or buildings have curved sides or when there are many corners that may not be square.  Even when you simply don't have the area for a lot and you need to calculate it using Photometrics can get you there.  The program will import only certain file types, so you have to change .PNG and other file types to .JPG files.

Yes of course there are problems using the Photometrics feature, importantly if you don't get the initial measurement correct when you import a graphic or drawing then every line that you create will have the wrong length.  So if your Photometrics sketch is telling you that every measurement that was made by the Assessor or by a Surveyor is wrong or every measurement that you made is wrong you could have a "scale" problem.  I like using Photometrics to confirm my measurements and not as the primary or sole method for determining site and building areas.

The built-in Photometrics feature is there so you should use it, especially when you are dealing with an atypical or complex property.  The feature may bring to your attention a problem that you would have overlooked.  I know that appraisers rarely make mistakes, but you never know, Photometics may help you feel better about your site and building area sketches.

For more appraisal information contact Glenn Rigdon, MA,MRICS, ASA a Las Vegas / Henderson Nevada appraiser via email or via his business website Horizon Village Appraisal (http://www.horizonvillageappraisal.com), or you can also click on “Contact Us” on the home page of this website. 

Article source: http://www.appraisalarticles.com/Appraisal-Software/3357-Photometrics.html