Examining the impact of Ground Control point quantity on the geometric accuracy of UAV photogrammetric products formed using Structure-from-Motion approach

The positional and vertical accuracy of UAV aerial photogrammetry products generated using the Structure from Motion (SfM) approach depends on various factors, such as flight plan parameters, camera quality, camera calibration, the SfM algorithm used, and the georeferencing process. The influence of the quantity of Ground Control Points (GCPs) on the geometric quality of generated models and the stability of camera calibration parameters assessed through self-calibration in the block-aerotriangulation process was investigated in this study. Three software systems were used to process the collected UAV photogrammetry images: Pix4D Mapper, Agisoft Metashape, and Trimble Inpho UASMaster. Standard statistical quality assessments were employed to assess the accuracy of the block-aerotriangulation. The research findings indicate that augmenting the quantity of GCPs enhances model reliability and decreases the RMSE values of vertical deviation on the control points. The RMSE values of vertical deviation on the check points for all three used software systems converged to approximately twice the value of the average spatial resolution. Additionally, the RMSE values of positional deviation on check points converged to the value of the average spatial resolution

Mechanical Properties of UV Cured Mixture of Linear and Hyperbranched Urethane Acrylates

Ispitivane su smeše uretan akrilata na bazi linearnog poliestra i dva uretan akrilata, sa istim stepenom akrilovanja, na bazi alifatskih hiperrazgranatih poliestara (HRP). Linearni poliestar sintetisan je od neopentil glikola i adipinske kiseline. HRP treće generacije dobijen je od 2,2- bis(hidroksimetil)propionske kiseline i di-trimetilol propana. Modifikacija 60 % završnih OH grupa HRP-a izvedena je masnim kiselinama sojinog ulja ili izononskom kiselinom. Linearni uretan akrilat (LUA) i hiperrazgranati uretan akrilat (HUA) na bazi HRP modifikovanog masnim kiselinama sojinog ulja i HUA na bazi HRP modifikovanog izononskom kiselinom dobijeni su reakcijom određenog poliestra i izocijanatnog adukta, prethodno dobijenog reakcijom ekvimolarnih količina izoforon diizocijanata i 2-hidroksietil akrilata. Procena mešljivosti smeša LUA i HUA izvršena je na osnovu viskozimetrijskih merenja koristeći metodu koju je ustanovio Chee. Ovako pripremljenim smešama dodato je 20 mas. % heksandioldiakrilata i 4 mas. % fotoinicijatora, Irgacure 184, i umrežene su pod dejstvom UV zračenja. Umreženi uzorci ispitivani su u ogledima dinamičkog uvijanja i jednoosnog istezanja. Mehanička svojstva umreženih uzoraka zavise od mešljivosti komponenata smeše i od njenog sastava.The mixtures of urethane acrylate resin based on linear polyester and two urethane acrylates, with the same degree of acrylation, prepared from partially modified aliphatic hyperbranched polyesters (HBP), were examined. Linear polyester was obtained from neopentil glycol and adipic acid. HBP of the third generation was synthesized from 2,2-bis(hydroxymethyl)propionic acid and ditrimethylol propane. The modification of 60 % OH end-groups of HBP was carried out with soybean fatty acids or isononanoic acid. Linear urethane acrylate (LUA) and hyperbranched urethane acrylate (HUA) based on the HBP modified with soy been faty acid and HUA based on the HBP modified with isononanoic acid were obtained by reaction of appropriate polyester and NCO adduct, previously obtained by reaction of equimolar amount of isophorone diisocyanate and 2-hydroxyethyl acrylate. The miscibility of the prepared mixtures of LUA and HUAs was estimated according to viscosity measurements using the approach developed by Chee. UV curable formulation was obtained by adding hexanediol diacrylate (20 wt. %) and photoinitiator, Irgacure 184, (4 wt. %) to the prepared LUA and HUA mixtures. The UV cured samples were examined by dynamic torsion and uniaxial tension. It was obtained that mechanical properties of the UV cured samples depend on miscibility of mixture’s constituents and on its composition

Synthesis of new hyperbranched urethane-acrylates and their evaluation in UV-curable coatings

Three series of hyperbranched urethane-acrylates (HB-UA), based on aliphatic hyperbranched polyesters and polyethyleneglycol acrylate, were prepared and evaluated for use in UV-curable coatings. UV-curing kinetics were monitored by FT-IR spectroscopy. The thermal and mechanical properties of UV-cured HB-UA were investigated by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and correlated to the mechanical properties of coatings (hardness and flexibility). These new HB-UA's are very reactive and did not show oxygen inhibition. Obtained coatings have good mechanical properties and solvent resistance

Dynamical mechanical analysis of photocrosslinked hyperbranched urethane acrylates

A series of acrylate functionalized samples based on hyperbranched hydroxy-terminated polyesters with different molecular weights and different degrees of acrylation were synthesized. The obtained urethane acrylates were slightly yellow viscose liquids. Their composition characterized by FTIR and H-1-NMR spectroscopy and their molecular weights were measured by GPC. All the synthesized samples were diluted with 25 wt.% 1.4-butanediol dimethacrylate (BDDM). The rheological properties of the uncured samples and the dynamic mechanical properties of the UV cured samples were examined. All the samples exhibit Newtonian behavior, which indicates the absence of physical entanglements in these polymers. The viscosity increases with increasing number of acrylic groups per molecule. The glass transition temperature of the UV cured samples increases with increasing the number of acrylic groups per molecule. The value of the storage modulus in the rubber-elastic plateau and the cross-link density increase with increasing number of acrylic groups per molecule. The formed networks are inhomogeneous and the residual unsaturation is the highest in the samples with the largest number of acrylic groups per molecule

UV-curable hyperbranched urethane acrylate oligomers containing soybean fatty acids

Urethane acrylate resins based on partially modified aliphatic hyperbranched polyesters (HBP) have been synthesized. HBP of the second and the third generation were synthesized from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylol propane. The modification of certain amount of OH end-groups was carried out with soybean fatty acids. The urethane acrylates with different degrees of acrylation have been obtained by reaction of partially modified HBP and different amounts of NCO adduct which had been previously obtained by reaction of equimolar amounts of isophorone diisocyanate and 2-hydroxyethyl acrylate. The synthesized samples were characterized by FT-IR,H-1 and C-13 NMR and GPC. The theological properties of uncured samples and mechanical and thermal properties of UV cured urethane acrylates diluted with 20 wt.% hexanediol diacrylate were examined. The modification of OH end-groups with soybean fatty acids causes a rapid decrease in viscosity of HBP. The examined properties of urethane acrylates depend on the degree of acrylation. After irradiating, the additional cross-linking, which is caused by reaction of double bonds from unsaturated fatty acids, has also important effect on the properties of cured samples

Photoreactive hyperbranched urethane acrylates modified with a branched saturated fatty acid

Urethane acrylate resins based on partially modified aliphatic hyperbranched polyesters (HBP) were synthesized. HBP of the second and the third pseudo-generation were synthesized from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylol propane. The modification of 60% of the OH end-groups was carried out with isononanoic acid. Urethane acrylates with different degrees of acrylation were obtained by reaction of partially modified HBP and different amounts of acrylate-isocyanate adduct (NCO), which had been previously obtained by reaction of equimolar amounts of isophorone diisocyanate and 2-hydroxyethyl acrylate. The synthesized samples were characterized by FT-IR, H-1 and C-13 NMR spectroscopy and GPC. The rheological properties of uncured samples and the mechanical and thermal properties of UV cured urethane acrylates diluted with 20 wt.% hexanediol diacrylate were examined. The modification of the OH end-groups with isononanoic acid caused a rapid decrease in the viscosity of the HBPs. The examined properties of the urethane acrylates mainly depended on the degree of acrylation

Synthesis and characterization of interpenetrating polymer networks with hyperbranched polymers through thermal-UV dual curing

The aim of this study was to investigate the possibility of using acrylated hyperbranched polyesters (HBP) as UV curable component in dual curing automotive applications. Dual curing is one of possible ways to obtain fast curing, scratch resistant coatings for use in OEM and car refinish applications. Dual curing systems, upon hardening, can give interpenetrating networks (IPNs). All the IPNs were obtained by UV-thermal dual cure process and they consisted of an UV curable acrylic component and a classic 2-pack urethane component. The acrylic component was acrylated hyperbranched polyester (HBP(A)) and 2-ethyl hexyl acrylate (EHA). The classic 2-pack urethane component consisted of a hydroxyl functional acrylate copolymer (HA) and Desniodur (R)) N3390. The weight ratio of HBP(A) and EHA in the IPNs was varied from 100/0 to 25/75, while the urethane component remained the same in all the IPN samples. The IPNs were characterized by dynamic-mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties of the IPNs were also investigated. A single glass transition temperature, T-g, indicated that a homogeneous material with no separation domain was obtained. DMA showed that with increasing HBP(A) in the IPNs, the crosslink density increased, while the flexibility decreased. The data obtained by DMA and DSC showed a decrease of the T-g values with increasing amount of HBP(A). There were slight differences in the thermal stability of the IPNs

The influence of different components on interpenetrating polymer network's (IPN's) characteristics as automotive top coats

The aim of this study was to investigate the influence of different components of interpenetrating polymer networks (IPNs) on their behavior in dual curing automotive applications. Dual curing is one of possible ways to obtain fast curing, scratch resistant coatings for use in OEM and car refinish applications. Dual curing systems, upon hardening, represent interpenetrating networks (IPNs) [1]. IPN's were obtained using novel acrylate-terminated hyperbranched polyester with high functionality and compared to classical 2-pack polyurethane clear coat. In our previous manuscript [1] we investigated the influence of the acrylated hyperbranched polyester (HBP(A)) content in dual curing systems. In this article we studied the influence of the reactive diluent on dual curing compositions. To this end, we have chosen IPN with 50/50 weigth ratio of polyurethane (PU) and polyacrylic (PA) component. In order to determine more clearly the role of the HBP(A) in one IPN HBP(A) was changed with hexane diol diacrylate (HDDA), keeping the same ratio with EHA. The IPNs were characterized by dynamic-mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties of the IPNs were also investigated. The IPN with HDDA as reactive diluent, had the best performance. IPN with H BP(A) had the highest glass transition temperature Tg and the highest crosslink density, but it did not have the highest hardness