Night vi­sion

Every skip­per dreads be­ing forced to a dif­fer­ent anchorage at night when it’s dif­fi­cult to see the sur­round­ings. FLIR ther­mal imag­ing tech­nol­ogy makes the job a lot eas­ier.

Boating NZ - - Boat Bling Profile - WORDS BY STEVE KER­SHAW – AB­SO­LUTE MARINE PHO­TOG­RA­PHY SUPPLIED

AFLIR (For­ward Look­ing In­frared) cam­era is par­tic­u­larly use­ful when nav­i­gat­ing around a dark bay filled with moored craft.

The units be­gan ap­pear­ing on New Zealand recre­ational boats around 2006, but the tech­nol­ogy dates to 1978 and was first geared to avi­a­tion sys­tems. To­day FLIR is the world’s largest pro­ducer of ther­mal cam­eras and is listed on the NAS­DAQ ex­change with a mar­ket cap­i­tal of over $5 bil­lion.

HOW FLIR WORKS

FLIR cam­eras de­tect only in­frared en­ergy (not light) and, as a re­sult, the lens of the unit uses a pricey rare me­tal called ger­ma­nium be­cause of its in­frared con­duct­ing abil­ity. The cam­eras can­not use a glass lens be­cause glass is a bar­rier to in­frared. Which is why FLIR units are usu­ally mounted out­side – on a ves­sel’s deck or su­per­struc­ture – and not in­side.

At the core of each cam­era is a de­vice called a mi­crobolome­ter. It de­tects in­frared ra­di­a­tion with wave­lengths of be­tween 7.5 and 14μm. A mi­crobolome­ter com­prises an ar­ray of pix­els that can be mea­sured and pro­cessed to cre­ate an im­age.

Every ob­ject emits in­frared en­ergy, re­gard­less of its tem­per­a­ture. Ob­jects at well be­low freez­ing are still vis­i­ble due to their in­frared foot­print, so even ice is easy to see. The dif­fer­ence be­tween in­frared and vis­i­ble light is the wave length. In­frared has a much longer wave length.

But there is a cor­re­la­tion be­tween the amount of in­frared light and the ac­tual tem­per­a­ture of an ob­ject. For this rea­son, the tech­nol­ogy’s been used for

decades for non-con­tact tem­per­a­ture mea­sure­ment. It’s use­ful for mea­sur­ing the tem­per­a­ture of very hot prod­ucts such as molten glass and steel.

For the most part, a FLIR im­age looks the same as one from a black and white video cam­era. But im­age de­tail is very clear and the unit will even de­tect de­bris in the water such as pieces of timber. This makes life eas­ier for skip­pers as there is no re­quire­ment to ‘in­ter­pret’ data or pat­terns. What you see is what you get.

HOW FAR?

FLIR splits its range spec­i­fi­ca­tion into two def­i­ni­tions – de­tec­tion and iden­ti­fi­ca­tion. De­tec­tion is the first point – when you clearly see an ob­ject ap­pear on your screen. Iden­ti­fi­ca­tion is when you clearly iden­tify the tar­get. For ex­am­ple, an im­age of a 50ft launch will be iden­ti­fied at a much greater dis­tance than a small run­about or kayak.

The com­pany pub­lishes a spec­i­fi­ca­tion ta­ble for all its cam­eras, so you can de­cide which model best suits your needs. Most recre­ational ves­sel units have a 320x240 mi­crobolome­ter. These can de­tect a four-me­tre ves­sel at around 1.9km (1nm) – ad­e­quate for col­li­sion avoid­ance even at speed.

Like all tech­nolo­gies there are lim­i­ta­tions and en­vi­ron­men­tal fac­tors will af­fect range. The height of the im­age rel­a­tive to the sea is an im­por­tant con­sid­er­a­tion, and the higher the cam­era is placed the bet­ter the im­age qual­ity and range.

Am­bi­ent air tem­per­a­ture, too, has an im­pact. A greater dif­fer­en­tial be­tween the sur­round­ings and a warm ob­ject will trans­late to sen­si­tiv­ity. In gen­eral, cooler, dry nights de­liver the best re­sults.

DUAL-PAY­LOAD

Har­bours and rivers that near cities can be af­fected by the heat cre­ated from cars, as­phalt and build­ings. Is­sues may arise di­rectly af­ter dusk as all this heat trans­lates to in­frared en­ergy. High lev­els can swamp the im­ager and greatly re­duce the sen­si­tiv­ity and re­duce the cam­era’s func­tion­al­ity.

But large cities also pro­vide large amounts of light and a qual­ity, low-light colour cam­era can work well. For this rea­son, FLIR in­tro­duced its dual-pay­load cam­era – a unit with both a FLIR and low-light func­tion. The com­bi­na­tion of the two tech­nolo­gies gives the skip­per the best of both worlds.

The FLIR cam­eras are gen­er­ally supplied with a 9-30Hz re­fresh rate. This refers to the up­date speed at which the screen gets in­for­ma­tion from the cam­era – 9Hz is nine times per sec­ond vs 30 times per sec­ond. Given that a FLIR unit points di­rectly ahead look­ing at ob­jects far away (rather than ob­jects moving rapidly from side to side), the re­fresh rate doesn’t have a ma­jor rel­e­vance for recre­ational boat­ies.

The higher the cam­era is placed the bet­ter the im­age qual­ity and range

THE M400

This is the premium cam­era within the M se­ries and offers two sig­nif­i­cant ben­e­fits. The first is min­imis­ing the rolling and pitch­ing of an im­age, as ex­pe­ri­enced in rough seas.

The M400 elec­tron­i­cally sta­bilises the im­age – just like a gyro. Sta­bil­i­sa­tion – com­bined with the new com­mu­ni­ca­tion in­ter­face – means that the M400 can now slew to cue and track from radar, AIS and chart­plot­ter sys­tems. The op­tional XR model has the added abil­ity to lock on to any video-se­lected tar­get on the screen – as set by the user – and track it.

NEW MOD­ELS

Ab­so­lute Marine has just taken delivery of FLIR’S lat­est M100 and M200 low-cost cam­eras. These offer sim­i­lar fea­tures to their pre­de­ces­sors, but are Eth­er­net-based and rely on a com­puter net­work to com­mu­ni­cate and dis­play the video im­age.

Later this year we ex­pect delivery of the next gen­er­a­tion of FLIR M-se­ries cam­eras. These new mod­els prom­ise even bet­ter im­age qual­ity and fea­ture the new-gen­er­a­tion FLIR cores. More sig­nif­i­cantly, they are all equipped with auto gyro-sta­bil­i­sa­tion.

In ad­di­tion, all the dual pay­load mod­els will up­grade from black and white day­light cam­eras to full colour. These new, lower cost units make it more af­ford­able for a new gen­er­a­tion of boat­ies to have FLIR as stan­dard equip­ment and make boat­ing safer at night.

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