简介:与传统宽波段成像系统相比,多光谱成像系统在性能表征、测试方法等方面有较大不同,而相关研究较为欠缺。因此,需要重点研究多光谱成像系统的综合性能评估方法。解决了目标光谱反射率等效控制、宽波段光谱维度的带内细分和标准靶标辐亮度调节等关键技术,设计了基于AOTF的多光谱成像系统二维鉴别率阈值测试平台及测试方法。在理论分析基础上,实际搭建了基于AOTF的可见光多光谱成像系统,叙述了系统标定方法和测试步骤,并基于所述方法在实验室条件下完成了系统空间分辨率、目标光谱反射率与对比度阈值的三维曲面测试实验。测试结果标明,所提出的方法可较好地反映不同谱段响应特性的差异,实现对多光谱成像系统的性能表征。基于该方法,可综合评估系统光谱分辨率、空间分辨率、灵敏度、对比度等性能指标,从而为多光谱成像系统性能的定量表征提供技术支持。
简介:长江后浪推前浪,在游戏行业尤其如此。随着硬件技术的提高,软件技术也不断地更新换代以提供缎带人们更好的视觉效果,游戏体验,但总有一些东西让你很难说清他们是否真的能被取代。或许有人说这仅仅是一种情怀,但不可否认有些东西的确有它自己独特的地方,因此而难以被取代,比如2D游戏。在如今3D游戏愈来愈流行的游戏行业,2D游戏的很多方面都显得过时,但是它所具有的一些优势的确是3D游戏所不具备的。相比3D游戏,它的团队规模更小,因此也更容易控制;它的动画制作相对3D要简单得多;而在编程方面2D游戏的控制也要简单得多;还有一点必须要说的就是2D游戏的像素艺术,或许有人说3D游戏在图像的表现方面优于像素艺术很多,但是不得不承认它给2D游戏的制作带来了很多有利条件,而青尧个人也很喜欢像素艺术。技术的进步对于游戏行业来说是一件好事,青尧说不好2D游戏是否会死去,但是我还是愿意祝福它能够走得更远。对这方面如果读者与青尧有不同的观点请与青尧联系:huoxiaoxia@cngda.com或在线投稿:http://tougao.chinagcn.com。
简介:Wetackletheproblemofconstructing2DcentroidalVoronoitessellationswithconstraintsthroughanefficientandrobustconstructionofboundedVoronoidiagrams,thepseudo-dualoftheconstrainedDelaunaytriangulation.WeexploitthefactthatthecellsoftheboundedVoronoidiagramcanbeobtainedbyclippingtheordinaryonesagainsttheconstrainedDelaunayedges.Theclippingitselfisefficientlycomputedbyidentifyingforeachconstrainededgethe(connected)setoftriangleswhosedualVoronoiverticesarehiddenbytheconstraint.TheresultingconstructionisamenabletoLloydrelaxationsoastoobtainacentroidaltessellationwithconstraints.
简介:Resortingtocubicsplinefunctioninsteadofparametricsplinerepresentation,anexplicitfairnessindicatorandanefficientfairingalgorithmfor2Dcurvesarepresented.Theinputpointsequenceisfirstlypartitionedintoseveraloverlappedfunctionsegments.Foreachsegment,acubicsplinefunctionisusedastherepresentationtoolwhichentailsapolylineapproximationofcurvatureplot.Basedontheextrinsicrelationshipbetweenthepolylineandthepositionsofdatapoints,acoarse-to-finefaringmethodisproposedwhichefficientlyidentifiesandeliminatestheunnecessaryinflectionpoints.Ouralgorithmgeneratesthebestresultstodate,whichisvalidatedbynumerouspracticalexamples.
简介:The2Dplanegasflowunderheating(withnonentityboundarycondition)hasbeendiscussedbytheanalyticalapproachinthispaper.Theapproximateanalyticalsolutionshavebeenobtainedfortheflowpassingvariouskindsofheatsources.Solutionsdemonstratethethermaldisplacementphenomenaarestronglydependontheheatingintensity.
简介:Cavitationisoneofthetroublesomeproblemsinrocketturbopumps,andsincemostofhigh-efficiencyrocketpropellantsarecryogenicfluids,socalled'thermodynamiceffect'becomesmoreevidentthaninwater.Inthepresentstudy.numericalandexperimentalstudyofliquidnitrogencavitationin2DLavalnozzlewascarriedout,sothattheinfluenceofthermodynamiceffectwasexamined.Itwasrevealedthattemperatureandcavitationhavestronginter-relationshipwitheachotherinthermo-sensitivecryogenicfluids.
简介:Thispaperproposesanewtechniquethatisusedtoembeddepthmapsintocorresponding2-dimensional(2D)images.Sincea2Dimageanditsdepthmapareintegratedintoonetypeofimageformat,theycanbetreatedasiftheywereone2Dimage.Thereby,itcanreducetheamountofdatain3Dimagesbyhalfandsimplifytheprocessesforsendingthemthroughnetworksbecausethesynchronizationbetweenimagesfortheleftandrighteyesbecomesunnecessary.Weembeddepthmapsinthequantizeddiscretecosinetransform(DCT)dataof2Dimages.Thekeytothistechniqueiswhetherthedepthmapscouldbeembeddedinto2Dimageswithoutperceivablydeterioratingtheirquality.Wetrytoreducetheirdeteriorationbycompressingthedepthmapdatabyusingthedifferencesfromthenextpixeltotheleft.Weassumethatthereisonlyonenon-zeropixelatmostononehorizontallineintheDCTblockbecausethedepthmapvalueschangeabruptly.Weconductanexperimenttoevaluatethequalityofthe2Dimagesembeddedwithdepthmapsandfindthatsatisfactoryqualitycouldbeachieved.
简介:Aseriesofidealizedmodelsimulationsareanalyzedtodeterminethesensitivityofmodelresultstodifferentconfigurationsofthelateralboundaryconditions(LBCs)insimulatingmesoscaleshallowconvectionoverhillyterrain.Inthesimulationswithsteadythermalforcingatthemodelsurface,aradiationconditionatbothboundariesisthebestchoiceunderhighwindconditions,andthebestresultsareproducedwhenboththenormalvelocitiesandthetemperaturearetreatedwiththeradiationschemeinwhichthephasespeedisthesamefordifferentvariables.Whenthebackgroundwindspeedisreasonablysmall,theLBCconfigurationwitheithertheradiationorthezerogradientconditionatbothboundariestendstomakethenumericalsolutionunstable.Thechoiceofaconstantconditionattheinflowboundaryandaradiationoutflowboundaryconditionisappropriateinmostcases.Inthesimulationswithdiurnalthermalforcingatthemodelsurface,differentLBCschemesarecombinedtogethertoreducespurioussignalsinducedbytheoutflowboundary.Aspecificationinflowboundarycondition,inwhichthevelocityfieldsattheinflowboundaryareprovidedusingthetime-dependentresultsofasimulationwithperiodicLBCsoveraflatdomain,istestedandtheresultsindicatethatthespecificationconditionattheinflowboundarymakesitpossibletouseasmallermodeldomaintoobtainreasonableresults.Themodelhorizontaldomainlengthshouldbegreaterthanacriticallength,whichdependsonthedomaindepthHandtheanglebetweengravitywavephaselinesandthevertical.Anestimateofminimumdomainlengthisgivenby[(H-zi)/πU]√N2L2x-4π2U2,whereNandUarethebackgroundstabilityandwindspeed,respectively,Lxisthetypicalgravitywavelengthscale,andziistheconvectiveboundarylayer(CBL)depth.