Ta yaya zan iya inganta daidaiton tsayi a cikin GPS TwoNav?

Preamble

Tun farkon 2021, IGN ke ba da damar samun dama ga wasu bayanan sa kyauta:

• Taswirorin TOP 25 na IGN ba su da kyauta tukuna, duk da haka sigar taswirar da ke kan Géoportil kyauta ce.
• Mahimman bayanai na IGN altimeter 5 x 5 m suna samuwa kyauta. Wadannan ma'ajin bayanai suna ba da damar ƙirƙirar samfurin ƙasa na dijital, watau. taswirar tsayi tare da ƙudurin kwance na 5 mx 5 m ko 1 mx 1 m tare da ƙuduri na tsaye na 1 m. Ko babban ma'anar masu amfani da mu.

Wannan labarin a cikin tsari na koyawa an yi niyya ne musamman don masu amfani da GPS TwoNav da software na Land.

Ba zai yiwu a yi tasiri ga bayanan tsayin GPS na Garmin a wannan lokacin ba.

Menene samfurin haɓakawa na dijital (DTM)

Samfurin haɓakawa na dijital (DEM) wakilci ne mai girma uku na saman duniya da aka ƙirƙira daga bayanan haɓakawa. Daidaiton fayil ɗin ɗagawa (DEM) ya dogara da:

• Ingantattun bayanan tsayi (daidaituwa da hanyoyin da ake amfani da su don binciken),
• Girman tantanin halitta (pixel),
• Game da daidaito a kwance na gano waɗannan grid,
• Daidaiton wurin wurin ku don haka ingancin GPS ɗin ku, agogon da aka haɗa ko wayar hannu.

Talle ko tayal daga IGN Altimetric database. 5 km x 5 km tile, wanda ya ƙunshi sel 1000 × 1000 ko 5 mx 5 m sel (Saint Gobain Aisne Forest). Ana hasashe wannan allon akan taswirar tushe na OSM.

DEM fayil ne wanda ke bayyana ƙimar tsayin wuri da ke tsakiyar grid, tare da gabaɗayan saman grid a tsayi ɗaya.

Misali, fayil ɗin sashen 5 x 5 m Aisne BD Alti IGN (sashen da aka zaɓa saboda girmansa) yana ƙarƙashin fale-falen 400 kawai.

Ana gano kowane grid ta hanyar daidaitawar latitude da longitude.

Karamin girman grid, mafi daidaitattun bayanan haɓakawa. Ba a yi watsi da cikakkun bayanan ɗauka ƙasa da girman raga (ƙudurin) ba.

Karamin girman raga, mafi girman daidaici, amma girman fayil ɗin zai kasance, don haka zai ɗauki ƙarin sararin ƙwaƙwalwar ajiya da wahala don aiwatarwa, mai yuwuwar rage sauran ayyukan sarrafawa.

Girman fayil ɗin DEM na sashen yana kusan 1Mo don 25m x 25m, 120Mo don 5m x 5m.

DEMs da yawancin apps, gidajen yanar gizo, GPS da wayoyi masu amfani ke amfani da su daga bayanan duniya kyauta ne da NASA ke bayarwa.

Tsarin daidaito na NASA DEM shine girman tantanin halitta na 60m x 90m da tsayin mataki na 30. Waɗannan fayiloli ne na asali, ba a gyara su ba, kuma sau da yawa ana haɗa bayanan, daidaito shine matsakaici, ana iya samun manyan. kurakurai.

Wannan yana daya daga cikin dalilan da ke haifar da rashin daidaiton GPS a tsaye, wanda ke bayyana bambancin tsayin da aka lura da waƙar, ya danganta da gidan yanar gizon da aka yi amfani da shi, GPS ko smartphone wanda ya rubuta bambancin tsayi.

• Sonny MNT (duba daga baya a cikin wannan jagorar) yana samuwa kyauta don Turai tare da girman tantanin halitta kusan 25m x 30m. Yana amfani da ingantattun hanyoyin bayanai fiye da NASA MNT kuma yayi aiki don magance manyan kwari. Yana da ingantacciyar ingantacciyar DEM wacce ta dace da hawan dutse, tare da kyakkyawan aiki a cikin ƙasar Turai.

A cikin hoton da ke sama, an canza tayal ɗin altimetric (MNT BD Alti IGN 5 x 5) wanda ke rufe tudun slag (kusa da Valenciennes) zuwa layin kwane-kwane da aka raba nisan mitoci 2,5 kuma an fifita su akan taswirar IGN. Hoton yana ba ku damar "lalata" a cikin ingancin wannan DEM.

• 5 x 5 m IGN DEM yana da ƙuduri na kwance (girman tantanin halitta) na 5 x 5 m da ƙuduri na tsaye na 1 m. Wannan DEM yana ba da haɓakar ƙasa; tsayin abubuwan ababen more rayuwa (ginai, gadoji, shinge, da sauransu) ba a la'akari da su ba. A cikin dajin, wannan shine tsayin ƙasa a gindin bishiyoyi, saman ruwa shine saman bakin tekun ga duk tafki mai girma fiye da hectare daya.

Taruwa da shigarwa na DEM

Don motsawa cikin sauri: Mai amfani da GPS TwoNav ya haɗa samfurin ƙasa na dijital wanda ke rufe Faransa ta amfani da bayanan IGN 5 x 5 m. Ana iya sauke waɗannan ta yanki daga rukunin yanar gizon kyauta: CDEM 5 m (RGEALTI).

Ga mai amfani, madaidaicin gwajin don tantance amincin "DEM" shine hangen nesa na saman tafkin a cikin 3D.

Ƙarƙashin tafkin tsofaffin jabu (Ardennes), wanda BD Alti IGN ya nuna a sama da BD Alti Sonny a ƙasa. Mun ga cewa akwai inganci.

Taswirar altimeter CDEM da TwoNav ke bayarwa a matsayin ma'auni don GPS ko software na LAND ba su da aminci sosai.

Don haka, wannan "koyawa" tana ba da jagorar mai amfani don zazzage "tiles" na amintattun bayanan altimetry na TwoNav GPS da software na LAND.

Ana samun bayanai kyauta don:

• Duk Turai: Sonny Altimetry Database,
• Faransa: IGN altimetry database.

Kuna iya ƙirƙirar fayil ɗin da ke rufe ƙasa, yanki ko yanki kawai (Slab / tile / Pellet) don adana ƙwaƙwalwar ajiya mai amfani ko amfani da ƙananan fayiloli.

Sonny Altimeters Database

An raba samfuran 1 '' zuwa 1 ° x1 ° fayil chunks kuma ana samun su a cikin tsarin SRTM (.hgt) tare da girman tantanin halitta 22 × 31 m dangane da latitude, tsarin da ake amfani da shi a duk duniya kuma ana amfani da shi a yawancin shirye-shirye. An tsara su ta hanyar haɗin gwiwar su, misali N43E004 (43 ° arewa latitude, 4 ° east longitude).

hanya

1. Haɗa zuwa rukunin yanar gizon https://data.opendataportal.at/dataset/dtm-france

2. Zazzage fale-falen fale-falen da suka dace da zaɓin ƙasa ko ɓangaren yanki.

3. Cire fayilolin .HGT daga fayilolin .ZIP da aka sauke.

4. A LAND, loda kowane fayil .HGT

5. A LAND, duk .hgts da ake so a buɗe suke, rufe sauran.

6. Da fatan za a yi "Haɗa waɗannan DEMS", lokacin tattarawa na iya zama tsayi dangane da adadin fale-falen fale-falen da za a tattara (zaɓi tsawo na cdem) don fayil ɗin .CDEM wanda za a iya amfani da shi akan Twonav GPS.

OSM "tile" da taswirar MNT "tile" a cikin LAND, komai yana ɗaukar hoto zuwa GPS kuma 100% kyauta!

IGN Altimetry Database

Wannan ma'ajin bayanai ya ƙunshi jagora ta sashe.

hanya

1. Haɗa zuwa rukunin yanar gizon Geoservices. Idan wannan hanyar haɗin yanar gizon ba ta aiki: burauzar ku "ba shi da damar FTP": kada ku firgita! Jagorar mai amfani:
   • A cikin mai sarrafa fayil ɗin ku:
   • dama danna "wannan PC"
   • dama danna "ƙara wurin cibiyar sadarwa"
   • Shigar da adireshin "ftp: // RGE_ALTI_ext: [e-mail]" "ba tare da" ";
   • Sunan wannan damar don gane ta tsohon IGN geoservice
   • Ƙarshen tsari
   • Jira ƴan mintuna kaɗan don sabunta jerin fayilolin (zai ɗauki ƴan mintuna)
2. Yanzu kuna da damar yin amfani da bayanan IGN:
   • Dama danna fayil ɗin bayanan da kake son kwafa.
   • Sa'an nan INSERT cikin manufa directory
   • Lokutan caji na iya daɗe!

Wannan hoton yana kwatanta shigo da rumbun adana bayanai na Vaucluse 5m x 5m. Danna dama akan fayil ɗin, sannan kwafi zuwa babban fayil kuma jira zazzagewa.

Bayan buɗe fayil ɗin "zipped", ana samun tsarin bishiyar. Bayanan sun yi daidai da fayilolin bayanai kusan 400 (tiles) 5 km x 5 km ko 1000 × 1000 cell 5 m x 5 m a cikin tsarin .asc (tsarin rubutu) don sashen.

Fayil ɗin tayal da yawa ya fi rufe hanyar MTB.

Kowane tantanin halitta 5x5 km ana gano shi ta saitin haɗin gwiwar Lambert 93.

Madaidaitan UTM na kusurwar hagu na sama na wannan tayal ko tayal sune x = 52 6940 da y = 5494 775:

• 775: Matsayin shafi (770, 775, 780, ...) akan taswira
• 6940: Sanya layi akan taswira

3. Rawa LAND

4. A mataki na gaba, nemo bayanai a cikin kundin “data”, zaɓi fayil na farko kawai:

5. Bude sannan tabbatarwa, taga na kasa zai bude, a yi hankali, wannan shine mafi m mataki :

Zaɓi tsinkayar Lambert-93 da Datum RGF 93 kuma duba akwatin a ƙananan kusurwar hagu.

Cire ƙasa da tsara bayanai daga * .asc tiles, wanda zai ɗauki ɗan lokaci.

Bayan ƙirƙirar slabs daga DEM a cikin tsarin SRTM (HGT / DEM), suna da yawa kamar yadda akwai fayiloli a tsarin * .asc.

6. Land yana ba ku damar "hada" su cikin fayil ɗin DEM guda ɗaya ko ta tayal ko granule don dacewa da bukatunku (ku tuna cewa girman fayil ɗin na iya rage aikin GPS)

Don sauƙin amfani, ya fi (na zaɓi) don rufe duk buɗaɗɗen katunan farko.

A cikin menu na taswira (duba ƙasa) buɗe duk fayiloli a cikin tsarin * .hdr (mafi ƙanƙanta mafi girma) na kundin bayanan bayanan da aka shigo da su (kamar yadda ayyukan da suka gabata)

Land yana buɗe fayilolin HDR, an ɗora DEM sashen kuma ana iya amfani dashi

7. Anan zaka iya amfani da Ardennes DEM (taswirar bump), don sauƙaƙa amfani da su, zamu haɗa su cikin fayil ɗaya.

Jerin menu:

Haɗa waɗannan DEMs

Zaɓi tsarin * .cdem kuma suna sunan fayil ɗin DEM.

Haɗin zai ɗauki ɗan lokaci kaɗan, fiye da fayiloli 21 suna buƙatar haɗa su. Don haka shawarar yin aiki akan tushen MNT granules da ke rufe wuraren wasan ku.

Mun ƙirƙiri samfurin dijital na filin Ardennes, kawai buɗe wannan fayil ɗin taswirar Geoportal na IGN kamar yadda aka nuna a ƙasa, misali.

Ana yin gwajin ta hanyar buɗe waƙar UtagawaVTT kai tsaye "Château de Linchamp" wanda aka nuna a farkon a tsayin tsayin 997m, 981m tare da Sonny DTM (tsari na baya) da 1034m lokacin da Land ya maye gurbin tsayi a kowane maki tare da tsayin DTM na 5mx5m .

Ƙididdigar bambancin matakin ta hanyar taƙaita layin kwane-kwane akan taswirar IGN yana nuna bambanci a matakin 1070 m, wato, bambancin 3%, wanda yayi daidai.

Ƙimar 1070 ta kasance mai ƙima saboda ba ƙaramin ƙididdigewa ba ne a lissafta lanƙwasa akan taswira cikin sauƙi.

Amfani da fayil altimetry

LAND na iya amfani da fayilolin MNT.cdem don cire haɓaka, ƙididdige tsayi, gangara, waƙoƙin hanya, da ƙari; kuma ga duk na'urorin GPS na TwoNav ya isa a saka fayil ɗin a cikin kundin adireshin / taswira kuma zaɓi shi azaman map.cdem.

Labarin blog akan tsayin da ba daidai ba yana bayyana matsalar tsayi da bambance-bambancen tsayi ta amfani da GPS, ana iya ɗaukar ƙa'idar zuwa agogon GPS da kuma aikace-aikacen wayar hannu.

Masu kera suna amfani da hanyoyi da yawa don "shafe" kuskuren da aka gabatar a cikin wannan labarin, tacewa (matsakaicin matsakaita) bayanan tsayi, ta amfani da firikwensin barometric ko samfurin ƙasa na dijital.

Matsayin GPS yana "ƙara", watau yana canzawa a kusa da matsakaicin darajar, tsayin daka na barometric ya dogara da yanayin matsa lamba na barometric da zazzabi, don haka yanayi da fayilolin DEM na iya zama kuskure.

Haɓakawa na barometer tare da GPS ko DEM yana dogara ne akan ƙa'ida mai zuwa:

• A cikin dogon lokaci, canjin yanayin barometric ya dogara da yanayin yanayi (matsi da zafin jiki),
• A cikin dogon lokaci, ana tace kurakuran tsayin GPS,
• Na dogon lokaci, kurakuran DEM suna kama da amo, don haka ana tace su.

Haɗin kai shine game da ƙididdige matsakaicin GPS ko tsayin DEM da cire canjin tsayi daga gare ta.

Misali, a cikin mintuna 30 na ƙarshe, tsayin tsawar da aka tace (GPS ko MNT) ya ƙaru da mita 100; duk da haka, a cikin wannan lokacin, tsayin da aka nuna ta barometer ya karu da mita 150.

A hankali, canjin tsayi ya kamata ya zama iri ɗaya. Sanin kaddarorin waɗannan na'urori masu auna firikwensin ya sa ya yiwu a "gyara" barometer -50 m.

Yawanci a cikin yanayin Baro + GPS ko 3D, ana gyara tsayin barometer, kamar yadda mai tafiya ko mai hawan dutse zai yi da hannu, ta hanyar nunin taswirar IGN.

Musamman, GPS ta kwanan nan ko wayar hannu ta kwanan nan (mai kyau) tana gano ku (FIX) tare da daidaiton 3,5 m a cikin jirgin sama na kwance sau 90 cikin 100 lokacin da yanayin liyafar ya dace.

Wannan "aiki" a kwance ya dace da girman raga na 5 mx 5 m ko 25 mx 25 m kuma amfani da waɗannan DTMs yana ba da damar daidaitattun daidaito.

DEM yana nuna tsayin ƙasa, misali idan kun haye kwarin Tarn akan Millau viaduct, waƙar da aka rubuta akan DEM yakamata ya kai ku zuwa ƙasan kwarin, koda kuwa hanyar ta kasance akan dandamalin viaduct. ...

Wani misali, lokacin da kake hawan dutse ko tafiya a gefen tsauni, daidaiton GPS a kwance yana lalacewa saboda abin rufe fuska ko tasirin hanyoyi masu yawa; to tsayin da aka sanya wa FIX zai yi daidai da tsayin dala mai kusa ko fiye da nisa, don haka ko dai zuwa sama ko zuwa gindin kwarin.

A cikin yanayin fayil ɗin da aka kafa ta grids na babban farfajiya, tsayin zai kasance zuwa matsakaici tsakanin kasan kwarin da saman!

Ga waɗannan matsananciyar misalan guda biyu amma na yau da kullun, ɗimbin bambancin tsayi zai karkata a hankali daga ƙimar gaskiya.

Shawarwari don amfani

Don guje wa illa:

• Yi ƙididdige ma'aunin barometer na GPS a tsayin wurin farawa jim kaɗan kafin tashi (duk masana'antun GPS sun ba da shawarar),
• bari GPS ɗinku ya yi ƴan gyare-gyare kafin fara bin sawu domin daidaiton matsayi ya dace,
• zaɓi haɓakawa: lissafin tsayi = Barometer + GPS ko Barometer + 3D.

Idan an daidaita hawan waƙar ku zuwa DEM, za ku sami daidaitattun ƙididdiga masu tsayi da gangara kamar a hoton da ke ƙasa, inda bambancin ya kai mita 1 kawai.

• Hanyar GPS 2 (72dpi wanda aka lalatar da hoto, allon GPS 200dpi)
• Mai rufi raster da taswirar vector OSM
• Ma'auni 1: 10
• CDEM 5mx5m BD Alti IGN shading yana jaddada tsayi a cikin haɓaka 1m.

Hoton da ke ƙasa yana kwatanta bayanin martaba na waƙoƙin 30km iri ɗaya (na shahara ɗaya), tsayin ɗayan an daidaita shi tare da IGN DEM kuma ɗayan tare da Sonny DEM, hanyar da ke gudana cikin yanayin baro + matasan 3d.

• Tsayi akan taswirar IGN: 275 m.
• An ƙididdige tsayin daka tare da GPS a cikin Yanayin Baro + 3D: 295 m (+ 7%)
• An ƙididdige tsayin daka tare da GPS a Yanayin Baro + GPS: 297 m (+ 8%).
• Hawan aiki tare akan IGN MNT: 271 m (-1,4%)
• Hawan aiki tare akan Sonny MNT: 255 m (-7%)

"Gaskiya" mai yiwuwa yana wajen IGN 275m saboda saitin lanƙwasa.

Misali na daidaitawa ta atomatik (diyya) na GPS barometric altimeter yayin hanyar da aka nuna a sama (Fayil log na asali daga GPS):

• Babu tarawa a tsaye don ƙididdige bambancin tsayi: 5 m, (Parametrization yayi kama da madaidaicin taswirar IGN),
• Matsayi yayin daidaitawa / sake saiti:
  • GPS 113.7m,
  • Barometric altimeter 115.0 m,
  • Tsawon MNT 110.2 m (Carte IGN 110 m),
• Juyawa (Lokacin Zama): Minti 30
• Gyaran Barometric na mintuna 30 masu zuwa: - 0.001297